diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Activity.m b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Activity.m
index eeb0d91d414aad76a6394296a1a520d13fb5f0a3..378413ea44949a59a50da7f271b5b89ff098fbd0 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Activity.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Activity.m
@@ -35,8 +35,7 @@
                                   callback(@[[NSNull null], results]);
                                   return;
                               } else {
-                                  NSLog(@"error getting active energy burned samples: %@", error);
-                                  callback(@[RCTMakeError(@"error getting active energy burned samples", nil, nil)]);
+                                  callback(@[RCTJSErrorFromNSError(error)]);
                                   return;
                               }
                           }];
@@ -65,8 +64,7 @@
                                   callback(@[[NSNull null], results]);
                                   return;
                               } else {
-                                  NSLog(@"error getting basal energy burned samples: %@", error);
-                                  callback(@[RCTMakeError(@"error getting basal energy burned samples", nil, nil)]);
+                                  callback(@[RCTJSErrorFromNSError(error)]);
                                   return;
                               }
                           }];
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.h b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.h
index 086797426969dc6bd3c069fdbb3cccfe2eefffe8..51b677164f95425856626796166d976036fe723d 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.h
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.h
@@ -23,6 +23,11 @@
 - (void)body_saveHeight:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
 
 - (void)body_getLatestBodyFatPercentage:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
+- (void)body_getBodyFatPercentageSamples:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
+- (void)body_saveBodyFatPercentage:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
+
 - (void)body_getLatestLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
+- (void)body_getLeanBodyMassSamples:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
+- (void)body_saveLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
 
 @end
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.m b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.m
index 34fd328837a07105f0872461669cc942ab2c3531..e3ba841eea59b09b0cca78469151f6ebef42cb0d 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.m
@@ -24,8 +24,7 @@
                                     predicate:nil
                                    completion:^(HKQuantity *mostRecentQuantity, NSDate *startDate, NSDate *endDate, NSError *error) {
         if (!mostRecentQuantity) {
-            NSLog(@"error getting latest weight: %@", error);
-            callback(@[RCTMakeError(@"error getting latest weight", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
         }
         else {
             // Determine the weight in the required unit.
@@ -67,8 +66,7 @@
             callback(@[[NSNull null], results]);
             return;
         } else {
-            NSLog(@"error getting weight samples: %@", error);
-            callback(@[RCTMakeError(@"error getting weight samples", nil, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
     }];
@@ -87,8 +85,7 @@
 
     [self.healthStore saveObject:weightSample withCompletion:^(BOOL success, NSError *error) {
         if (!success) {
-            NSLog(@"error saving the weight sample: %@", error);
-            callback(@[RCTMakeError(@"error saving the weight sample", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
         callback(@[[NSNull null], @(weight)]);
@@ -104,8 +101,7 @@
                                     predicate:nil
                                    completion:^(HKQuantity *mostRecentQuantity, NSDate *startDate, NSDate *endDate, NSError *error) {
         if (!mostRecentQuantity) {
-            NSLog(@"error getting latest BMI: %@", error);
-            callback(@[RCTMakeError(@"error getting latest BMI", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
         }
         else {
             // Determine the bmi in the required unit.
@@ -136,8 +132,7 @@
 
     [self.healthStore saveObject:bmiSample withCompletion:^(BOOL success, NSError *error) {
         if (!success) {
-            NSLog(@"error saving BMI sample: %@.", error);
-            callback(@[RCTMakeError(@"error saving BMI sample", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
         callback(@[[NSNull null], @(bmi)]);
@@ -198,8 +193,7 @@
           callback(@[[NSNull null], results]);
           return;
         } else {
-          NSLog(@"error getting height samples: %@", error);
-          callback(@[RCTMakeError(@"error getting height samples", error, nil)]);
+          callback(@[RCTJSErrorFromNSError(error)]);
           return;
         }
     }];
@@ -218,8 +212,7 @@
 
     [self.healthStore saveObject:heightSample withCompletion:^(BOOL success, NSError *error) {
         if (!success) {
-            NSLog(@"error saving height sample: %@", error);
-            callback(@[RCTMakeError(@"error saving height sample", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
         callback(@[[NSNull null], @(height)]);
@@ -235,8 +228,7 @@
                                     predicate:nil
                                    completion:^(HKQuantity *mostRecentQuantity, NSDate *startDate, NSDate *endDate, NSError *error) {
         if (!mostRecentQuantity) {
-            NSLog(@"error getting latest body fat percentage: %@", error);
-            callback(@[RCTMakeError(@"error getting latest body fat percentage", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
         }
         else {
             // Determine the weight in the required unit.
@@ -257,6 +249,62 @@
 }
 
 
+- (void)body_getBodyFatPercentageSamples:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback
+{
+    HKQuantityType *bodyFatPercentType = [HKQuantityType quantityTypeForIdentifier:HKQuantityTypeIdentifierBodyFatPercentage];
+    
+    HKUnit *unit = [HKUnit percentUnit];
+    NSUInteger limit = [RCTAppleHealthKit uintFromOptions:input key:@"limit" withDefault:HKObjectQueryNoLimit];
+    BOOL ascending = [RCTAppleHealthKit boolFromOptions:input key:@"ascending" withDefault:false];
+    NSDate *startDate = [RCTAppleHealthKit dateFromOptions:input key:@"startDate" withDefault:nil];
+    NSDate *endDate = [RCTAppleHealthKit dateFromOptions:input key:@"endDate" withDefault:[NSDate date]];
+    if(startDate == nil){
+        callback(@[RCTMakeError(@"startDate is required in options", nil, nil)]);
+        return;
+    }
+    NSPredicate * predicate = [RCTAppleHealthKit predicateForSamplesBetweenDates:startDate endDate:endDate];
+    
+    [self fetchQuantitySamplesOfType:bodyFatPercentType
+                                unit:unit
+                           predicate:predicate
+                           ascending:ascending
+                               limit:limit
+                          completion:^(NSArray *results, NSError *error) {
+                              if(results){
+                                  callback(@[[NSNull null], results]);
+                                  return;
+                              } else {
+                                  NSLog(@"error getting body fat percentage samples: %@", error);
+                                  callback(@[RCTMakeError(@"error getting body fat percentage samples", nil, nil)]);
+                                  return;
+                              }
+                          }];
+}
+
+
+- (void)body_saveBodyFatPercentage:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback
+{
+    double percentage = [RCTAppleHealthKit doubleValueFromOptions:input];
+    NSDate *sampleDate = [RCTAppleHealthKit dateFromOptionsDefaultNow:input];
+    HKUnit *unit = [HKUnit percentUnit];
+    
+    percentage = percentage / 100;
+
+    HKQuantity *bodyFatPercentQuantity = [HKQuantity quantityWithUnit:unit doubleValue:percentage];
+    HKQuantityType *bodyFatPercentType = [HKQuantityType quantityTypeForIdentifier:HKQuantityTypeIdentifierBodyFatPercentage];
+    HKQuantitySample *bodyFatPercentSample = [HKQuantitySample quantitySampleWithType:bodyFatPercentType quantity:bodyFatPercentQuantity startDate:sampleDate endDate:sampleDate];
+    
+    [self.healthStore saveObject:bodyFatPercentSample withCompletion:^(BOOL success, NSError *error) {
+        if (!success) {
+            NSLog(@"error saving body fat percent sample: %@", error);
+            callback(@[RCTMakeError(@"error saving body fat percent sample", error, nil)]);
+            return;
+        }
+        callback(@[[NSNull null], @(percentage)]);
+    }];
+}
+
+
 - (void)body_getLatestLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback
 {
     HKQuantityType *leanBodyMassType = [HKQuantityType quantityTypeForIdentifier:HKQuantityTypeIdentifierLeanBodyMass];
@@ -265,8 +313,7 @@
                                     predicate:nil
                                    completion:^(HKQuantity *mostRecentQuantity, NSDate *startDate, NSDate *endDate, NSError *error) {
         if (!mostRecentQuantity) {
-            NSLog(@"error getting latest lean body mass: %@", error);
-            callback(@[RCTMakeError(@"error getting latest lean body mass", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
         }
         else {
             HKUnit *weightUnit = [HKUnit poundUnit];
@@ -283,4 +330,58 @@
     }];
 }
 
+
+- (void)body_getLeanBodyMassSamples:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback
+{
+    HKQuantityType *leanBodyMassType = [HKQuantityType quantityTypeForIdentifier:HKQuantityTypeIdentifierLeanBodyMass];
+    
+    HKUnit *unit = [RCTAppleHealthKit hkUnitFromOptions:input key:@"unit" withDefault:[HKUnit poundUnit]];
+    NSUInteger limit = [RCTAppleHealthKit uintFromOptions:input key:@"limit" withDefault:HKObjectQueryNoLimit];
+    BOOL ascending = [RCTAppleHealthKit boolFromOptions:input key:@"ascending" withDefault:false];
+    NSDate *startDate = [RCTAppleHealthKit dateFromOptions:input key:@"startDate" withDefault:nil];
+    NSDate *endDate = [RCTAppleHealthKit dateFromOptions:input key:@"endDate" withDefault:[NSDate date]];
+    if(startDate == nil){
+        callback(@[RCTMakeError(@"startDate is required in options", nil, nil)]);
+        return;
+    }
+    NSPredicate * predicate = [RCTAppleHealthKit predicateForSamplesBetweenDates:startDate endDate:endDate];
+    
+    [self fetchQuantitySamplesOfType:leanBodyMassType
+                                unit:unit
+                           predicate:predicate
+                           ascending:ascending
+                               limit:limit
+                          completion:^(NSArray *results, NSError *error) {
+                              if(results){
+                                  callback(@[[NSNull null], results]);
+                                  return;
+                              } else {
+                                  NSLog(@"error getting lean body mass samples: %@", error);
+                                  callback(@[RCTMakeError(@"error getting lean body mass samples", nil, nil)]);
+                                  return;
+                              }
+                          }];
+}
+
+
+- (void)body_saveLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback
+{
+    double mass = [RCTAppleHealthKit doubleValueFromOptions:input];
+    NSDate *sampleDate = [RCTAppleHealthKit dateFromOptions:input key:@"startDate" withDefault:[NSDate date]];
+    HKUnit *unit = [RCTAppleHealthKit hkUnitFromOptions:input key:@"unit" withDefault:[HKUnit poundUnit]];
+    
+    HKQuantity *massQuantity = [HKQuantity quantityWithUnit:unit doubleValue:mass];
+    HKQuantityType *massType = [HKQuantityType quantityTypeForIdentifier:HKQuantityTypeIdentifierLeanBodyMass];
+    HKQuantitySample *massSample = [HKQuantitySample quantitySampleWithType:massType quantity:massQuantity startDate:sampleDate endDate:sampleDate];
+    
+    [self.healthStore saveObject:massSample withCompletion:^(BOOL success, NSError *error) {
+        if (!success) {
+            NSLog(@"error saving lean body mass sample: %@", error);
+            callback(@[RCTMakeError(@"error saving lean body mass sample", error, nil)]);
+            return;
+        }
+        callback(@[[NSNull null], @(mass)]);
+    }];
+}
+
 @end
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Characteristic.m b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Characteristic.m
index e030b856567d5cb131769f438c87492062382d07..e6266a9325a3d6113f83999c8be36002a5ec118c 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Characteristic.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Characteristic.m
@@ -34,8 +34,7 @@
     }
 
     if(value == nil){
-        NSLog(@"error getting biological sex: %@", error);
-        callback(@[RCTMakeError(@"error getting biological sex", error, nil)]);
+        callback(@[RCTJSErrorFromNSError(error)]);
         return;
     }
 
@@ -52,8 +51,7 @@
     NSDate *dob = [self.healthStore dateOfBirthWithError:&error];
 
     if(error != nil){
-        NSLog(@"error getting date of birth: %@", error);
-        callback(@[RCTMakeError(@"error getting date of birth", error, nil)]);
+        callback(@[RCTJSErrorFromNSError(error)]);
         return;
     }
     if(dob == nil) {
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Fitness.m b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Fitness.m
index bd8261bb9726e919f7ddd2fd21cb53edddb03074..6ca17408675c52085c8f43862799f9d10c05ae87 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Fitness.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Fitness.m
@@ -34,8 +34,7 @@
                                     day:date
                              completion:^(double value, NSDate *startDate, NSDate *endDate, NSError *error) {
         if (!value) {
-            NSLog(@"could not fetch step count for day: %@", error);
-            callback(@[RCTMakeError(@"could not fetch step count for day", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
 
@@ -123,8 +122,7 @@
                                            includeManuallyAdded:includeManuallyAdded
                                       completion:^(NSArray *arr, NSError *err){
         if (err != nil) {
-            NSLog(@"error with fetchCumulativeSumStatisticsCollection: %@", err);
-            callback(@[RCTMakeError(@"error with fetchCumulativeSumStatisticsCollection", err, nil)]);
+            callback(@[RCTJSErrorFromNSError(err)]);
             return;
         }
         callback(@[[NSNull null], arr]);
@@ -150,8 +148,7 @@
 
     [self.healthStore saveObject:sample withCompletion:^(BOOL success, NSError *error) {
         if (!success) {
-            NSLog(@"An error occured saving the step count sample %@. The error was: %@.", sample, error);
-            callback(@[RCTMakeError(@"An error occured saving the step count sample", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
         callback(@[[NSNull null], @(value)]);
@@ -173,9 +170,7 @@
                      NSError *error) {
 
          if (error) {
-             // Perform Proper Error Handling Here...
-             NSLog(@"*** An error occured while setting up the stepCount observer. %@ ***", error.localizedDescription);
-             callback(@[RCTMakeError(@"An error occured while setting up the stepCount observer", error, nil)]);
+             callback(@[RCTJSErrorFromNSError(error)]);
              return;
          }
 
@@ -200,8 +195,7 @@
 
     [self fetchSumOfSamplesOnDayForType:quantityType unit:unit day:date completion:^(double distance, NSDate *startDate, NSDate *endDate, NSError *error) {
         if (!distance) {
-            NSLog(@"ERROR getting DistanceWalkingRunning: %@", error);
-            callback(@[RCTMakeError(@"ERROR getting DistanceWalkingRunning", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
 
@@ -276,8 +270,7 @@
                                            includeManuallyAdded:includeManuallyAdded
                                       completion:^(NSArray *arr, NSError *err){
                                           if (err != nil) {
-                                              NSLog(@"error with fetchCumulativeSumStatisticsCollection: %@", err);
-                                              callback(@[RCTMakeError(@"error with fetchCumulativeSumStatisticsCollection", err, nil)]);
+                                              callback(@[RCTJSErrorFromNSError(err)]);
                                               return;
                                           }
                                           callback(@[[NSNull null], arr]);
@@ -293,8 +286,7 @@
 
     [self fetchSumOfSamplesOnDayForType:quantityType unit:unit day:date completion:^(double distance, NSDate *startDate, NSDate *endDate, NSError *error) {
         if (!distance) {
-            NSLog(@"ERROR getting DistanceCycling: %@", error);
-            callback(@[RCTMakeError(@"ERROR getting DistanceCycling", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
 
@@ -334,8 +326,7 @@
                                            includeManuallyAdded:includeManuallyAdded
                                       completion:^(NSArray *arr, NSError *err){
                                           if (err != nil) {
-                                              NSLog(@"error with fetchCumulativeSumStatisticsCollection: %@", err);
-                                              callback(@[RCTMakeError(@"error with fetchCumulativeSumStatisticsCollection", err, nil)]);
+                                              callback(@[RCTJSErrorFromNSError(err)]);
                                               return;
                                           }
                                           callback(@[[NSNull null], arr]);
@@ -351,8 +342,7 @@
 
     [self fetchSumOfSamplesOnDayForType:quantityType unit:unit day:date completion:^(double count, NSDate *startDate, NSDate *endDate, NSError *error) {
         if (!count) {
-            NSLog(@"ERROR getting FlightsClimbed: %@", error);
-            callback(@[RCTMakeError(@"ERROR getting FlightsClimbed", error, nil), @(count)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
 
@@ -388,8 +378,7 @@
                                            limit:limit
                                       completion:^(NSArray *arr, NSError *err){
                                           if (err != nil) {
-                                              NSLog(@"error with fetchCumulativeSumStatisticsCollection: %@", err);
-                                              callback(@[RCTMakeError(@"error with fetchCumulativeSumStatisticsCollection", err, nil)]);
+                                              callback(@[RCTJSErrorFromNSError(err)]);
                                               return;
                                           }
                                           callback(@[[NSNull null], arr]);
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Mindfulness.m b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Mindfulness.m
index b14ef8137a7bc7618f8de087aaf906137d3a0a46..1dc6dca911494dd8dbed44a365ae6e14617bcfc7 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Mindfulness.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Mindfulness.m
@@ -29,8 +29,7 @@
 
     [self.healthStore saveObject:sample withCompletion:^(BOOL success, NSError *error) {
         if (!success) {
-            NSLog(@"An error occured saving the mindful session sample %@. The error was: %@.", sample, error);
-            callback(@[RCTMakeError(@"An error occured saving the mindful session sample", error, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
         callback(@[[NSNull null], @(value)]);
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Results.m b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Results.m
index fd5d0345ceb2278a59782f10b15913de0f3dc434..a1c1cdea6e96786add9f59ca7e190f3e6a18a7b5 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Results.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Results.m
@@ -32,8 +32,7 @@
             callback(@[[NSNull null], results]);
             return;
         } else {
-            NSLog(@"error getting blood glucose samples: %@", error);
-            callback(@[RCTMakeError(@"error getting blood glucose samples", nil, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
     }];
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Sleep.m b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Sleep.m
index faba4ed1739c4367fddc4158937ac85ad7a2c1ff..0894624e47c329825d8c3474df11ae933d4e0406 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Sleep.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Sleep.m
@@ -36,8 +36,7 @@
                                              callback(@[[NSNull null], results]);
                                              return;
                                          } else {
-                                             NSLog(@"error getting sleep samples: %@", error);
-                                             callback(@[RCTMakeError(@"error getting sleep samples", nil, nil)]);
+                                             callback(@[RCTJSErrorFromNSError(error)]);
                                              return;
                                          }
                                      }];
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Vitals.m b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Vitals.m
index 74c53cb74cdab407ada69d6ca2e4bc4326fc31db..698a1b25b825d010a3017a2fafd3429dd1839137 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Vitals.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+Methods_Vitals.m
@@ -33,8 +33,7 @@
             callback(@[[NSNull null], results]);
             return;
         } else {
-            NSLog(@"error getting heart rate samples: %@", error);
-            callback(@[RCTMakeError(@"error getting heart rate samples", nil, nil)]);
+            callback(@[RCTJSErrorFromNSError(error)]);
             return;
         }
     }];
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+TypesAndPermissions.h b/RCTAppleHealthKit/RCTAppleHealthKit+TypesAndPermissions.h
index d69b7e956a6376bd2fea3d26128bdfc0ed97f908..c6668c69654043f6727b54f1df1c457d82e85caf 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+TypesAndPermissions.h
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+TypesAndPermissions.h
@@ -15,5 +15,7 @@
 - (NSDictionary *)writePermsDict;
 - (NSSet *)getReadPermsFromOptions:(NSArray *)options;
 - (NSSet *)getWritePermsFromOptions:(NSArray *)options;
+- (HKObjectType *)getWritePermFromString:(NSString *)string;
+- (NSString *)getAuthorizationStatusString:(HKAuthorizationStatus)status;
 
 @end
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit+TypesAndPermissions.m b/RCTAppleHealthKit/RCTAppleHealthKit+TypesAndPermissions.m
index 8d0c930173529ed23da75e4ef4627fe38540f13d..a54f03fb80a47d3030312b714e74f225ecefdcd1 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit+TypesAndPermissions.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit+TypesAndPermissions.m
@@ -153,4 +153,18 @@
     return writePermSet;
 }
 
+- (HKObjectType *)getWritePermFromString:(NSString *)writePerm {
+    return [[self writePermsDict] objectForKey:writePerm];
+}
+- (NSString *)getAuthorizationStatusString:(HKAuthorizationStatus)status {
+    switch (status) {
+        case HKAuthorizationStatusNotDetermined:
+            return @"NotDetermined";
+        case HKAuthorizationStatusSharingDenied:
+            return @"SharingDenied";
+        case HKAuthorizationStatusSharingAuthorized:
+            return @"SharingAuthorized";
+    }
+}
+
 @end
diff --git a/RCTAppleHealthKit/RCTAppleHealthKit.m b/RCTAppleHealthKit/RCTAppleHealthKit.m
index df459c43b1630cc391bf37f5c91e3d8178f3b635..e2b13587d65be4f5e3c593811f52ed70e3c70a8c 100644
--- a/RCTAppleHealthKit/RCTAppleHealthKit.m
+++ b/RCTAppleHealthKit/RCTAppleHealthKit.m
@@ -99,11 +99,31 @@ RCT_EXPORT_METHOD(getLatestBodyFatPercentage:(NSDictionary *)input callback:(RCT
     [self body_getLatestBodyFatPercentage:input callback:callback];
 }
 
+RCT_EXPORT_METHOD(getBodyFatPercentageSamples:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback)
+{
+    [self body_getBodyFatPercentageSamples:input callback:callback];
+}
+
+RCT_EXPORT_METHOD(saveBodyFatPercentage:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback)
+{
+    [self body_saveBodyFatPercentage:input callback:callback];
+}
+
 RCT_EXPORT_METHOD(getLatestLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback)
 {
     [self body_getLatestLeanBodyMass:input callback:callback];
 }
 
+RCT_EXPORT_METHOD(getLeanBodyMassSamples:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback)
+{
+    [self body_getLeanBodyMassSamples:input callback:callback];
+}
+
+RCT_EXPORT_METHOD(saveLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback)
+{
+    [self body_saveLeanBodyMass:input callback:callback];
+}
+
 RCT_EXPORT_METHOD(getStepCount:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback)
 {
     [self fitness_getStepCountOnDay:input callback:callback];
@@ -271,9 +291,7 @@ RCT_EXPORT_METHOD(saveMindfulSession:(NSDictionary *)input callback:(RCTResponse
 
         [self.healthStore requestAuthorizationToShareTypes:writeDataTypes readTypes:readDataTypes completion:^(BOOL success, NSError *error) {
             if (!success) {
-                NSString *errMsg = [NSString stringWithFormat:@"Error with HealthKit authorization: %@", error];
-                NSLog(errMsg);
-                callback(@[RCTMakeError(errMsg, nil, nil)]);
+                callback(@[RCTJSErrorFromNSError(error)]);
                 return;
             } else {
                 dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
@@ -286,6 +304,28 @@ RCT_EXPORT_METHOD(saveMindfulSession:(NSDictionary *)input callback:(RCTResponse
     }
 }
 
+RCT_EXPORT_METHOD(authorizationStatusForType:(NSString *)type
+                  resolver:(RCTPromiseResolveBlock)resolve
+                  rejecter:(RCTPromiseRejectBlock)reject
+{
+    if (self.healthStore == nil) {
+        self.healthStore = [[HKHealthStore alloc] init];
+    }
+
+    if ([HKHealthStore isHealthDataAvailable]) {
+        HKObjectType *objectType = [self getWritePermFromString:type];
+        if (objectType == nil) {
+            reject(@"unknown write permission", nil, nil);
+            return;
+        }
+
+        NSString *status = [self getAuthorizationStatusString:[self.healthStore authorizationStatusForType:objectType]];
+        resolve(status);
+    } else {
+        reject(@"HealthKit data is not available", nil, nil);
+    }
+})
+
 - (void)getModuleInfo:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback
 {
     NSDictionary *info = @{
diff --git a/README.md b/README.md
index c0df2ee1f56c9506f6c3c7e100d1835ab047672b..6ad3ead0b94a3ba6b0b69298479f6a2b39a8495c 100644
--- a/README.md
+++ b/README.md
@@ -106,6 +106,7 @@ AppleHealthKit.initHealthKit(options: Object, (err: string, results: Object) =>
     * Base Methods
       * [isAvailable](/docs/isAvailable().md)
       * [initHealthKit](/docs/initHealthKit().md)
+      * [authorizationStatusForType](/docs/authorizationStatusForType().md)
     * Realtime Methods
       * [initStepCountObserver](/docs/initStepCountObserver().md)
       * [setObserver](/docs/setObserver().md)
@@ -129,8 +130,10 @@ AppleHealthKit.initHealthKit(options: Object, (err: string, results: Object) =>
       * [getHeightSamples](/docs/getHeightSamples().md)
       * [getLatestBmi](/docs/getLatestBmi().md)
       * [getLatestBodyFatPercentage](/docs/getLatestBodyFatPercentage().md)
+      * [getBodyFatPercentageSamples](/docs/getBodyFatPercentageSamples().md)
       * [getLatestHeight](/docs/getLatestHeight().md)
       * [getLatestLeanBodyMass](/docs/getLatestLeanBodyMass().md)
+      * [getLeanBodyMassSamples](/docs/getLeanBodyMassSamples().md)
       * [getLatestWeight](/docs/getLatestWeight().md)
       * [getRespiratoryRateSamples](/docs/getRespiratoryRateSamples().md)
       * [getSleepSamples](/docs/getSleepSamples().md)
@@ -143,6 +146,8 @@ AppleHealthKit.initHealthKit(options: Object, (err: string, results: Object) =>
       * [saveMindfulSession](/docs/saveMindfulSession().md)
       * [saveWeight](/docs/saveWeight().md)
       * [saveSteps](/docs/saveSteps().md)
+      * [saveBodyFatPercentage](/docs/saveBodyFatPercentage().md)
+      * [saveLeanBodyMass](/docs/saveLeanBodyMass().md)
   * [References](#references)
 
 ## Supported Apple Permissions
@@ -172,6 +177,7 @@ The available Healthkit permissions to use with `initHealthKit`
 | StepCount              | [HKQuantityTypeIdentifierStepCount](https://developer.apple.com/reference/Healthkit/hkquantitytypeidentifierstepcount?language=objc)                               | ✓    | ✓     |
 | Steps                  | [HKQuantityTypeIdentifierSteps](https://developer.apple.com/reference/Healthkit/hkquantitytypeidentifiersteps?language=objc)                                       | ✓    | ✓     |
 | Weight                 | [HKQuantityTypeIdentifierBodyMass](https://developer.apple.com/reference/Healthkit/hkquantitytypeidentifierbodymass?language=objc)                                 | ✓    | ✓     |
+| BodyFatPercentage      | [HKQuantityTypeIdentifierBodyFatPercentage](https://developer.apple.com/reference/Healthkit/hkquantitytypeidentifierbodyfatpercentage?language=objc)                                 | ✓    | ✓     |
 
 These permissions are exported as constants of the `rn-apple-healthkit` module.
 
diff --git a/docs/authorizationStatusForType().md b/docs/authorizationStatusForType().md
new file mode 100644
index 0000000000000000000000000000000000000000..8687b89b926df11f8348d2f46bbd5d2587454d30
--- /dev/null
+++ b/docs/authorizationStatusForType().md
@@ -0,0 +1,16 @@
+Check the authorization status for sharing (writing) the specified data type.
+
+Status will be one of `"NotDetermined"`, `"SharingDenied"`, `"SharingAuthorized"`.
+
+```javascript
+try {
+const status = await AppleHealthKit.authorizationStatusForType("StepCount")
+if (status) {
+  console.log("status is", status)
+}
+} catch (error) {
+  console.warn(error)
+}
+```
+
+There is no way to check authorization status for read permission, [see this](https://developer.apple.com/documentation/healthkit/hkhealthstore/1614154-authorizationstatusfortype?language=objc).
diff --git a/docs/getBodyFatPercentageSamples().md b/docs/getBodyFatPercentageSamples().md
new file mode 100644
index 0000000000000000000000000000000000000000..8e3e872296efed719e906f9938445d2f0c0de77d
--- /dev/null
+++ b/docs/getBodyFatPercentageSamples().md
@@ -0,0 +1,27 @@
+Query for body fat percentage samples. the options object is used to setup a query to retrieve relevant samples.
+
+```javascript
+let options = {
+  startDate: (new Date(2016,4,27)).toISOString(), // required
+  endDate: (new Date()).toISOString(), // optional; default now
+  ascending: false,	// optional; default false
+  limit:10, // optional; default no limit
+};
+```
+
+```javascript
+AppleHealthKit.getBodyFatPercentageSamples(options, (err: Object, results: Array<Object>) => {
+  if (err) {
+    return;
+  }
+  console.log(results)
+});
+```
+
+```javascript
+[
+  { value: 16.5, startDate: '2016-07-09T00:00:00.000-0400', endDate: '2016-07-10T00:00:00.000-0400' },
+  { value: 16.1, startDate: '2016-07-08T00:00:00.000-0400', endDate: '2016-07-09T00:00:00.000-0400' },
+  { value: 15.9, startDate: '2016-07-07T00:00:00.000-0400', endDate: '2016-07-08T00:00:00.000-0400' },
+]
+```
diff --git a/docs/getLeanBodyMassSamples().md b/docs/getLeanBodyMassSamples().md
new file mode 100644
index 0000000000000000000000000000000000000000..93a0af87b066ad9222e84b35b8bcca365a9d5b04
--- /dev/null
+++ b/docs/getLeanBodyMassSamples().md
@@ -0,0 +1,28 @@
+Query for lean body mass samples. the options object is used to setup a query to retrieve relevant samples.
+
+```javascript
+let options = {
+  unit: 'pound', // optional; default 'pound'
+  startDate: (new Date(2016,4,27)).toISOString(), // required
+  endDate: (new Date()).toISOString(), // optional; default now
+  ascending: false,	// optional; default false
+  limit:10, // optional; default no limit
+};
+```
+
+```javascript
+AppleHealthKit.getLeanBodyMassSamples(options, (err: Object, results: Array<Object>) => {
+  if (err) {
+    return;
+  }
+  console.log(results)
+});
+```
+
+```javascript
+[
+  { value: 160, startDate: '2016-07-09T00:00:00.000-0400', endDate: '2016-07-10T00:00:00.000-0400' },
+  { value: 161, startDate: '2016-07-08T00:00:00.000-0400', endDate: '2016-07-09T00:00:00.000-0400' },
+  { value: 165, startDate: '2016-07-07T00:00:00.000-0400', endDate: '2016-07-08T00:00:00.000-0400' },
+]
+```
diff --git a/docs/saveBodyFatPercentage().md b/docs/saveBodyFatPercentage().md
new file mode 100644
index 0000000000000000000000000000000000000000..e5f2bc39e36855e1c3a5e6673842f6cc2e5cbb30
--- /dev/null
+++ b/docs/saveBodyFatPercentage().md
@@ -0,0 +1,17 @@
+save a percentage body fat value to Healthkit
+
+`saveBodyFatPercentage` accepts an options object containing a percent value:
+```javascript
+let options = {
+  value: 16.7 // 16.7%
+}
+```
+
+```javascript
+AppleHealthKit.saveBodyFatPercentage(options: Object, (err: Object, results: Object) => {
+  if (err) {
+    return;
+  }
+  // body fat percentage successfully saved
+});
+```
diff --git a/docs/saveLeanBodyMass().md b/docs/saveLeanBodyMass().md
new file mode 100644
index 0000000000000000000000000000000000000000..44b7a317f29c0d905c21a6dfd2e949ee43e15c3d
--- /dev/null
+++ b/docs/saveLeanBodyMass().md
@@ -0,0 +1,18 @@
+save a numeric lean body mass value to Healthkit
+
+`saveLeanBodyMass` accepts an options object containing a numeric weight value:
+```javascript
+let options = {
+  value: 155.6 // lbs
+}
+```
+
+```javascript
+AppleHealthKit.saveLeanBodyMass(options: Object, (err: Object, results: Object) => {
+    if (err) {
+        console.log("error saving lean body mass to Healthkit: ", err);
+        return;
+    }
+    // Done
+});
+```