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Why am I losing weight but not body fat percentage?
January 21, 2010 10:12 AM   Subscribe

I'm losing weight but my body fat percentage isn't changing much. Should I change something or just be more patient?

After being thin most my life, I put on about 100 pounds over the past five years and became almost completely sedentary (bad reaction to stress, lots of comfort and boredom eating and drinking). In September I started doing Weight Watchers and going to the gym, with the goal of losing 100 pounds.

I've lost 50 pounds at a pretty steady rate of two pounds a week (sometimes a little less, sometimes a little more). My BMI has gone from 36.8 to 30.1 (so I am still fat). I have a scale that measures body fat percentage, but I haven't been tracking body fat percentage the way I have the weight. However, I have recently realized that it's stayed around 44% for the past month. I honestly don't remember what it was when I started but I know it was in the 40's. So, at most, my body fat percentage has gone down maybe 5%.

So, my question is WTF body fat, basically. I thought losing weight the way I have been--averaging two pounds a week, eating when I'm hungry, not starving myself--was the way to lose fat, not muscle. And yet, I am just about as fat, as a percentage of my body weight, as I was when I started.

Possibly relevant info--I've been eating within my WW points range, although not eating fruits or veggies at all until very recently. (There was a question here recently about green smoothies, which are awesome! And I've had more fruits and veggies in the past week and a half than in the past year, probably. Seriously, I have had a hell of time making myself eat veggies. Bu I lost more weight this week than usual.) I don't really want to eat more to slow down my weight loss because I am trying to only eat when I'm hungry. Eating more would require eating when I'm not hungry.

I have been working out with a personal trainer twice a week doing mostly body-weight circuit type stuff--lots of lunges and squats combined with presses and curls with dumbbells and lots of core. I also do 30-45 minutes on the elliptical 3-5 times a week. I've been focusing on getting my sedentary butt moving again, hence all the cardio. I can definitely see a big difference in my strength and fitness level, which is another thing that makes me feel very frustrated about the body fat percentage. I just don't feel like I'm still carrying as much fat as I was. And if I'm stronger, shouldn't that equate to me gaining muscle mass, not losing it?

So, I guess I'm wondering if anyone has an opinion about this. Am I still just so fat that I won't start seeing real changes in the percentage until I lose more? Is the scale wrong? Should I be doing something different? Should I stop worrying about the number and just focus on how I feel?
posted by Mavri to Health & Fitness (22 answers total)
 
The scale may well be wrong. According to this article at Consumer Reports' website, when they tested body-fat-measuring scales a few years ago, the scales only got the measurements right 80% of the time.

And personally, I wouldn't worry about the number. You've done good work losing the 50 lbs., and as long as you're feeling good (and your blood chemistry's okay), there's little point in focusing on it.
posted by asterix at 10:19 AM on January 21, 2010


This isn't a problem with your methods but rather with the tools you are using to track your progress. Body fat scales are -terrible- at actually measuring body fat. You can't count on it to accurately measure or track a trend with your body fat.

The easiest way is to use a measuring tape and track your waist (not hip) circumference but it's likely that if you feel less fat you -ARE- less fat.
posted by Loto at 10:19 AM on January 21, 2010


I think the last thing you said is key.

Home body fat scales are notoriously inaccurate. If the number is super important to you, you should get a hydrostatic test in a water tank in a lab or sports clinic.

I think the gains you are seeing in strength and fitness (and the weight you are losing!) are much more meaningful. Can you walk faster and longer, lift heavier things, are your measurements changing? Do you feel better throughout the day? There's proof of your success, right there.
posted by peachfuzz at 10:19 AM on January 21, 2010


The scale is probably wrong.
posted by jingzuo at 10:21 AM on January 21, 2010


I'm really not sure how a scale can take a single value - your weight - and somehow magically divine what percentage of your body is fat vs anything else. And the weaknesses of BMI are pretty well-documented.

You're losing weight at a phenomenal rate, keeping to a diet, working out with a trainer, and feeling a lot better. You are, in fact, doing everything right. Don't worry about semi-meaningless numbers like "body fat percentage" unless a doctor tells you to - the important thing here is, do you like how your body is looking? Do you like the trend you see? Do you like how you feel? If the answer is "yes," then you're doing the right things, and you should keep them up.
posted by Tomorrowful at 10:22 AM on January 21, 2010 [1 favorite]


My scale has the same feature, and I'll tell you a weird wrinkle: at night, my BF % is always at least 4 points lower than in the AM. Conclusion: can't rely on the scale to assess BF %. You may want to see if the same thing goes on with yours -- that'll prove you needn't worry about this.

This unreliablity of my scale makes me wonder why I joined the MeFi body fat challenge, but oh well.
posted by bearwife at 10:28 AM on January 21, 2010


For a person of your size and body composition, BEI will not work, period. Don't sweat it. Keep doing what you've been doing.
posted by jock@law at 10:30 AM on January 21, 2010


Dont rely on electronic body fat calculators... the best way to get measured is a dunk tank, after that is someone who knows what they are doing with calipers, but even this can be off a couple of % points each day and you need someone who consistently knows what they are doing.

If you can find a water dunk tank near you get it done, then dont worry about it and go back in 6 months. Also, do NOT compare this number with any other bodyfat number, whatever you thought your bfat was when you started was probably inaccurate, just use the dunk number as a new baseline to monitor progress. Check with local colleges, most college athletic facilities will dunk you for a small fee.

if you are still losing weight and have another 50lbs to lose you dont need to worry about body composition at this point, you WILL be losing fat so dont sweat it, and you are probably putting on muscle, or at least retaining the muscle it took to move that extra 50 lbs around all day!

If your fitness level is going up and your weight is going down who cares about some random electronic number?
posted by outsider at 10:46 AM on January 21, 2010


Keep on going and don't worry about the numbers.
posted by bunny hugger at 10:48 AM on January 21, 2010


Yeah, scales are mostly crap, particularly at the higher and lower ends of the scale. This morning, for fun, I hopped on both before and after my run and my bf% had changed by half a percent.

Don't sweat it!
posted by restless_nomad at 10:50 AM on January 21, 2010


Body fat percentage scales work by sending an electrical current up through your body, and measures how long it takes to return to the scale. The current moves slower through fat than through other tissues, so measuring the speed of current return measures your body fat. (For a much more science-y explaination, see here.)

If you are drinking a lot of water as part of your weight loss efforts, that can throw off the scale's accuracy. (And bearwife, it makes sense that your body fat % would be lower at night, because you are filled with food and possibly dehydrated from your day, thus making the proportion of your weight that's water be lower).

So yes, again: its probably the scale, not you. Keep up the good work!
posted by Kololo at 10:52 AM on January 21, 2010


Two things you should consider:

First, as stated above, the idea that a scale can correctly assess BMI is perverse at best. Don't overthink the statistical side of this. If you are losing weight, feel stronger and enjoy the life you are living, you are on the right track.

Which brings us to my second point. It took you five years to get to the place you found yourself in. You have traveled six months away from it. During those five years your body did a lot of things to accommodate your weight gain including adding muscle density in certain areas just to make it possible for you to walk and move about. It takes time for your body to change back to accommodating the "new" you. Keep doing what you are doing and realize that your body needs time to do what it is doing in response to these changes. If you feel good and can see yourself attaining your fundamental goals, whether you have a BMI of X or Y or Z is not really that important.

Enjoy the new you.
posted by Old Geezer at 10:56 AM on January 21, 2010


Don't worry about semi-meaningless numbers like "body fat percentage" unless a doctor tells you to

Bodyfat percentage is not a meaningless number, the problem is just that the scale may not be accurate, as everyone has pointed out.

And if I'm stronger, shouldn't that equate to me gaining muscle mass, not losing it?

Not necessarily. Strength gains can come from increased neural efficiency, which basically means training your body to better utilize the muscle you already have rather than creating new muscle tissue. This effect is most pronounced when using heavy weights (see this table for a more detailed breakdown), but an untrained person will get stronger by doing just about anything.

Anyhow, you talk about eating lots of veggies, but you didn't say anything about protein. To maintain muscle mass while losing fat it's essential that your protein intake is adequate.

You also mention bodyweight exercises, which are useful, but keep in mind that if you want to build strength and bone density, you'll want to use progressive loading, which means incrementally increasing the weight of your resistance movements. And remember that any weighted exercise performed on your feet, e.g. the squat, the deadlift, or the press, is also a "core" exercise.
posted by ludwig_van at 11:04 AM on January 21, 2010


Just here to echo ludwig_van's thoughts about protein. If you're losing weight by eating a lot of baked potatoes, you're going to lose muscle mass even if you are strength training. Your body needs protein to build muscle.
posted by Aleen at 11:08 AM on January 21, 2010


The thing is, saying "my bodyfat is only down 5%" is wrong.

What's down 5% is the dodgy number the scales produce. That number is merely a somewhat effective, but often completely wrong gimmick. You are clearly making progress. If you are really concerned about accurate bodyfat measurement, get a proper caliper reading done.
posted by i_am_joe's_spleen at 11:23 AM on January 21, 2010


Yes, the scales are crap, but that doesn't mean there isn't an issue here. I am by no means an expert, a trainer, or anything like that, so take this with a grain of salt. But:

I once designed a three-month walking program for myself. I got dunk tank tested at the beginning and end of it. What I did was just get a good pedometer, and up my average steps per day every week for the three months. Weighed myself every morning, but didn't track body fat with a scale at all.

I didn't really change my diet for the better - in fact it got a little worse as I discovered that I could do stuff like have ice cream every night and still lose weight. That was good motivation, but maybe not such a good idea in the long run.

I did indeed lose weight, about 17 lbs. over the three months, but my bodyfat percentage was almost unchanged. The lab that tested me worked out my lean mass and fat mass, and they both declined almost in lockstep. In light of what I've learned since then, I blame two things: my diet was pretty heavy on carbs and low on protein, and I was doing pure cardio with no strength training at all to build new muscle.

You are doing some weight work, but it seems to be a pretty small part of your workouts compared to the cardio. I might try to expand the weight portions a little bit. And I'm even less qualified to talk about your diet, but more protein is good, sugar and other processed carbs not so good.
posted by Naberius at 11:35 AM on January 21, 2010


These scales are not particularly accurate, and vary depending on hydration and electrolyte status. You can verify this on your own by comparing morning readings to evening readings when you
-consume an extra 5-6 glasses of water, or dehydrate yourself in a sauna/steamroom
-eat a couple bananas

A better way to track body fat loss is to use a pair of body calipers, that measure skinfold thickness. Choose say 8-10 sites (cheek, pec, stomach by bellybutton, love handle, upper back above scapula, below scapula, mid thight, kneecap, calf). Measure the skinfold thickness there each day and it should provide you a consistent and more reliable to measure your bodyfat change.

There's also no doubt you've gained a couple pounds of muscle mass from the five workouts a week you mentioned performing.
posted by zentrification at 11:37 AM on January 21, 2010


Thanks everybody. The trainer and I have been adding some more weight stuff, and I will try to do more of that on my own. (I've been trying not to overwhelm myself with too many changes at once--perfect is the enemy of the good, baby steps, etc., but I think I can add weights now.)

As for the diet, it never occurred to me that I might not be getting enough protein. I just did a quick calculation and I think I get between 40 and 75 grams a day (depending entirely on what I eat for dinner b/c I have the same thing for breakfast and lunch every day). I eat half a whole-wheat English muffin with natural (no sugar added) peanut butter about an hour before I go to the gym (both because I have a small lunch and get hungry in the late afternoon and because I was exhausted at the gym before I started doing this). I've had almost no candy, sweets, desserts, soda, or alcohol since I started this in September. My diet is much better than it was, but my diet was pretty appalling before (comfort food galore), so there's certainly room to improve.
posted by Mavri at 12:36 PM on January 21, 2010


If you are drinking a lot of water as part of your weight loss efforts, that can throw off the scale's accuracy. (And bearwife, it makes sense that your body fat % would be lower at night, because you are filled with food and possibly dehydrated from your day, thus making the proportion of your weight that's water be lower).

I think you have it backwards, the more hydrated you are the lower your body fat reading will be, which is why for people that drink a decent amount of water during the day they read lower body fat (but higher weight) at night than in the morning.

I use one of those scales, and I don't think it is particularly accurate in that I don't actually think I am exactly that body fat percentage, but I think it is fairly consistent, and the body fat reading does go up and down with my changes in fat and muscle mass. So, if your body fat reading hasn't changed much in 50 pounds, you probably are losing lean and fat mass at approximately the same weight. That might be ok for the first 50 pounds, but you will start to feel it with the next 50 as it becomes that much harder to lose weight period.

Definitely eat more protein, I'm shocked you aren't starving on 40g a day (it really helps immensely with satiety). Up those weights or even just do the stuff you do with your trainer more often. You don't need to sit on the elliptical more than a couple of times a week. Better to do 3 days of weights and 2 days of elliptical than the other way around. I highly recommend that if you are currently using the WW thing of "burn off points to earn points to eat" you cut that out, because it encourages mindless cardio to a detrimental degree.
posted by ch1x0r at 4:42 PM on January 21, 2010


Should I change something or just be more patient?

Be patient, you are doing great. Everything you're doing is fine and you should continue what you are doing. As far as all the other question, do you have a specific goal? Is it a specific amount of weight loss or a specific bodyfat percentage you want to be at? Do you want to build a substantial amount of muscle? Do you have a strength goal? Pick one goal you want to achieve and concentrate on that. Once you get there then reassess. You'll find that most of your worries about all the other things will not only go away but it will have been for nothing because things fall into place usually; i.e. you're worried about bodyfat but when it's all said and done and you've lost the weight you won't care about bodyfat percentages.
posted by P.o.B. at 8:19 PM on January 21, 2010


Just keep doing what you're doing, loosing 50 lbs is awesome! It's one of those things where you will plateau here and there, but if you keep watching what you eat you will be amazed at how you can change your body -

"I've had almost no candy, sweets, desserts, soda, or alcohol"

Try totally and completely eliminating all of the above. Actually, you can have a vodka with soda water here and there, but the only sweets should be whole natural fruit. Maybe with plain yogurt that has noooooo sugar added. It will be really hard for about 2 weeks, but once your body adjusts and you try drinking even a diet soda you will see how outrageously sweet it is. You can graduate to honey, which is super sweet and can satisfy a craving.

It's a whole different outlook on eating - as little sugar and processed foods as possible. You will feel awesome and you will loose more weight, I promise! Once you get used to it for a while (like a month or two) you will be able to indulge a little here and there, but when your system has been readjusted to healthy eating, and you try a sticky cinnamon bun, you will experience it as it truly is - sickeningly sweet and doughy. (But delicious all the same).

//end rant
posted by smartypantz at 12:46 AM on January 22, 2010


Two important words that I don't see mentioned so far: 1) mirror and 2) intervals.

1) The mirror is probably a better gauge than the fat percentage number of that scale. Are you happy with your results when you look in the mirror? Get acquainted with both the things you like about your body when you look at yourself, and the things you don't like so much. Then look again at those areas every week or month. Hopefully the bad stuff will be getting better and the good stuff will stay the same or even improve. If you're up for it, document changes with pictures. I expect you notice progress...if you don't...

2) Try including some interval work in your cardio. Push yourself as hard as you can for 30 seconds, then slow it down for 60. Do this for at least 20 minutes of your 30-45 minutes of cardio (with 5 minutes of warm up / cool down pace at beginning/end). As you progress, try upping the sprints to 45 seconds, then 60. You should be completely breathless by the end of your sprints, unable to hold a conversation certainly. Ideally during the last 10 seconds your body should be telling you can't possibly finish the interval...you have to train your mind to push past those limits your body has adapted as 'normal' for the last 5 years. (Of course IANAD, listen to any pain outside of your muscles/heart, etc.) If the elliptical machine can display strides per minute, you should be aiming for at least 200.

Finally, you should be switching up your exercise routine somewhat every 6 months or so. Take a spin class on one or two of your cardio days, for example. It's all about constantly making the body adapt to new stimuli. Though, hopefully, your trainer has got variety covered for you.
posted by and hosted from Uranus at 9:41 AM on January 22, 2010


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