Please help me understand Tanita scale reading...

This is a wordy post, but I'm Hoping someone can help me interpret the Tanita Scale reading from my most recent nutritionist appointment. It's a hospital-based weight management program so I am confident in the nutritionist's knowledge. Here's some background:
June 13-- exercise from previous month included running/walking and some circuit training. Eating at about 1300 cal/day.
Scale readings:
Standard body type, weight 190
fat 40.5%
fat mass 77 lb
muscle mass 107 lb
BMR 1578

July 19--exercise up to here included Insanity! 3x/week, running 2x/week. Eating about 1300 cal/day
Scale reading:
Standard body type, weight 186
Fat 36%
Water 84 lb
Fat mass 68 lb
Muscle mass 112 lb
BMR 1622

I was very happy with these results! My body felt stronger, I saw some changes in my shoulders and upper body, and I felt stronger. This was encouraging!

Sept 9-- i was very motivated, so exercise up to here included 6 days a week. Started New Rules of Lifting For Women Aug 1 and did stage 1 every other day religiously. Saw consistent gains in strength. On non-lifting days, either did Insanity! or run 3 miles and walk 1.5 miles. I was feeling stronger and more confident with lifting. My own scale went up when I started lifting, as expected, so I stopped weighing myself mid-Aug. I was more hungry, so I averaged about 1450-1500 cal/day.
Scale reading:
Standard body type, weight 189
Fat 38.5%
Water 83 lb
Fat mass 73 lb
Muscle mass 110 lb
BMR 1608

So this reading just blew my mind! How could my fat go up and muscle mass go down?? I shared my MFP food log and exercise routine with nutritionist and she was as confused as me. Then she asked what my resting heart rate was....between 58-65 bpm. Based on this and the fact that I have steadily increased my exercise to nearly 7 hours per week, she suggested changing the body type on the Tanita Scale to "ATHLETIC" and weighing me again. I didn't even know that you could do that! So, here's what came up:
Athletic body type, weight 189
fat 29.8%
Water 94 lb
Fat mass 56 lb
Muscle mass 126 lb
BMR 1787

Nutritionist said that the "athletic mode" accounts for more water weight. She was not specific with her explanation but said the best comparison will be made when I am weighed again in 8 weeks with the Athletic body type setting. You cannot compare readings with different body types. However, I need to keep up my exercise to stay within this body type. She increased my calories to 1700/day which really scares me. I mean, I have plenty of fat-storage, so the mention of "starvation mode" just doesn't fly with me. My body has not changed very much...I see a little more definition in my shoulders, but my pants aren't any looser.

I am getting pretty frustrated and Any suggestions or ideas would be appreciated. Thanks!!!

Replies

  • Here are some guidelines when using a Tanita scale:

    The weight of fat in a person's body is unlikely to change by a large amount during the course of a day: In the same way that the bones and internal organs do not change. However, the weight of a person's body is constantly changing as food and water is taken in and passed out.

    In addition, a person's hydration status is changing constantly - this is water contained not in the stomach, but in the muscle tissue where it is needed for the body to function. So why does the body fat % change? It is important to remember that the reading shows the PERCENTAGE of your total weight that is fat, not the actual WEIGHT of fat. So, mathematically, if your total weight goes up because you have more water in your body, the percentage of your weight that is fat will be lower even though the actual weight of fat has not changed.

    Conversely, if you are dehydrated, your total weight will be lower giving a higher % of fat. This is easier to see with scales that show total body water because as the water % increases the fat % decreases and vice versa.

    To obtain the greatest accuracy and repeatability from our product, Tanita suggests the following protocol.

    - Take readings at least 3 hours after rising, eating a large meal, or exercising. We suggest taking a reading before your evening meal.
    - Take readings once a week at the same time of day under the same conditions. (Note: Taking readings more than once per week is not beneficial since body fat does not change from day to day.)
    - Average your readings for the month.
    - Compare averages from month to month.

    The athlete mode is for adults who have approximately 10 hours of intense physical activity (this does not include beginners) and have a resting heart rate of approximately 60 beats per minute or less.