Metabolism and weight loss

[Minoosh]

From "Time" magazine:

What Hall discovered, however--and what frankly startled him--was that even when the Biggest Loser contestants gained back some of their weight, their resting metabolism didn't speed up along with it. Instead, in a cruel twist, it remained low, burning about 700 fewer calories per day than it did before they started losing weight in the first place. "When people see the slowing metabolism numbers," says Hall, "their eyes bulge like, How is that even possible?"

I don't see how it's even possible either. Burning 700 calories less a day means adding a pound a week. This wasn't particularly healthy weight loss as it encourages crash dieting and muscle mass may be loss. The person also doesn't have to lug that weight around but this was resting metabolism. Maybe they are resting far more than they did while dieting? I'm not sure how resting metabolism is measured. But I don't understand the physical mechanism that would allow the body to be maintained on 700 fewer calories a day.

Does this sound strange to anyone else?

 

[The Don]

The way it was explained to me (but which could be absolute bunkum) was that, all other things considered, the heavier you are, the higher your basal metabolic rate (BMR). This is because living material requires at least some energy to maintain it.

As it was explained to me, muscle requires far more energy than fat so if you have more lean muscle mass (or less fat) for the same bodyweight then you'll have a higher BMR.

Over the course of a series, some people on The Biggest Loser lose 50% or more of their bodyweight. They may put on some muscle (but then again they may not, if you're very heavy and still mobile then there has to be some muscle in there somewhere ) but likely not enough to metabolically offset the couple of hundreds of pounds of they have lost.

All of the above could be the sort of errant nonsense that gets talked by the sort of people who really don't understand human physiology but that's what I was led to believe.

 

[Dr. Keith]

To add more unfounded speculation: it costs energy just to keep that excess mass at body temperature. The math may not work out to that being the major factor, but it has to be part of the equation.

 

[Ziggurat]

From "Time" magazine:

Your link is messed up. Here's the correct link.

I don't see how it's even possible either. Burning 700 calories less a day means adding a pound a week. This wasn't particularly healthy weight loss as it encourages crash dieting and muscle mass may be loss. The person also doesn't have to lug that weight around but this was resting metabolism. Maybe they are resting far more than they did while dieting? I'm not sure how resting metabolism is measured. But I don't understand the physical mechanism that would allow the body to be maintained on 700 fewer calories a day.

Does this sound strange to anyone else?

Notice what's missing from this article: any discussion of muscle mass. In fact, the word "muscle" doesn't appear anywhere in the article at all. Muscle mass is a critical component of metabolism, but it is frequently ignored. It shouldn't be.

One reason is that measuring total body weight is easy, but accurately measuring muscle mass is difficult. Another is that most people have very little concept of how to efficiently increase muscle mass (other than steroids). This even includes people who should know, like exercise science professors.

One of the posters above said they didn't know if the contestants lost muscle mass. This is basically guaranteed. First, the exercises that the contestants are doing are not exercises that will build muscle mass. Second, on a severely calorie-restricted diet, your protein intake is likely to be restricted as well, and you need protein to build and even maintain muscle. Third, when you're severely calorie-restricted, fat isn't the only thing that your body will metabolize to make up the difference. You will metabolize muscle tissue as well.

Fat people tend to have a lot of muscle as well, simply because you need more muscle to more more body weight. The proportion of muscle to fat is much worse than for skinny people, but the absolute amount is usually higher. But if you crash diet, you lose both muscle and fat. If you don't exercise specifically to keep as much muscle as possible (and those contestants don't), then you might end up as skinny as a normally skinny person, but with less muscle and more fat. And that's bad for you. It's not sustainable.

 

[Minoosh]

One reason is that measuring total body weight is easy, but accurately measuring muscle mass is difficult. Another is that most people have very little concept of how to efficiently increase muscle mass (other than steroids). This even includes people who should know, like exercise science professors.

Thanks for fixing the link.

I was in a study more than 30 years ago that required I be weighed while under water - to the best of my recollection. That was to determine how much of my weight was fat, since fat floats and muscle doesn't. I do have very strong haunches (I am female) and if I get the gluteal workouts going it's like I have a booster engine burning more fuel.

At a gym I went to about 14 years ago there was a glute machine, like a face-down hamstring machine but with the bar falling mid-thigh vs. down toward the ankle area. You didn't lie down, I was more or less on my hands and knees. I could max out on it. Upper body not strong though. There also used to be a type of sit-down ab machine where you used both your upper and lower body to squeeze toward the center. I've never seen these type of machines again, though I have been in a few reasonably equipped gyms. I wonder if there was some safety issue with them.

 

[Ziggurat]

At a gym I went to about 14 years ago there was a glute machine, like a face-down hamstring machine but with the bar falling mid-thigh vs. down toward the ankle area. You didn't lie down, I was more or less on my hands and knees. I could max out on it. Upper body not strong though. There also used to be a type of sit-down ab machine where you used both your upper and lower body to squeeze toward the center. I've never seen these type of machines again, though I have been in a few reasonably equipped gyms. I wonder if there was some safety issue with them.

Forget the machines. Barbell squats and deadlifts are superior. Better range of motion, and works more muscle mass. Plus you can load it in smaller increments and to higher weights.

 

[The_Animus]

From what I've read, and my own personal experience confirms, The Don and Ziggurat are correct.

 

[blutoski]

From "Time" magazine:



I don't see how it's even possible either. Burning 700 calories less a day means adding a pound a week. This wasn't particularly healthy weight loss as it encourages crash dieting and muscle mass may be loss. The person also doesn't have to lug that weight around but this was resting metabolism. Maybe they are resting far more than they did while dieting? I'm not sure how resting metabolism is measured. But I don't understand the physical mechanism that would allow the body to be maintained on 700 fewer calories a day.

Does this sound strange to anyone else?

It does, and it sounded strange to a lot of researchers, so there are a few blogs and other writings that explain it.

Basically... the research was not designed to test the effect of rapid weight loss on BMR. It was designed to test a newly proposed alternative mechanism for calculating BMR, and for some reason they chose contestants from a reality TV show to be their test population.

There's no control group, and the results sound wacky, so the best explanation is actually: "Nope. The new BMR formula doesn't work, you're getting spurious results. Back to the woodshed."



ETA... here's a link to the abstract. Notice the date... the Time article is referencing a 5 year old study that has been widely refuted as bogus. Bit of a journalism fail, IMO. [Metabolic Slowing with Massive Weight Loss despite Preservation of Fat-Free Mass]

 

[blutoski]

It does, and it sounded strange to a lot of researchers, so there are a few blogs and other writings that explain it.

Basically... the research was not designed to test the effect of rapid weight loss on BMR. It was designed to test a newly proposed alternative mechanism for calculating BMR, and for some reason they chose contestants from a reality TV show to be their test population.

There's no control group, and the results sound wacky, so the best explanation is actually: "Nope. The new BMR formula doesn't work, you're getting spurious results. Back to the woodshed."

Just as a comparison... there is already a body of research about the BMR effect of rapid and large scale weight loss. None of the previous research shows this 'effect'. Consider the dramatic effects from bariatric, for example, that typically exceed the rate of loss seen on Biggest Loser, and often more net weight loss too.

eg: [Long-term changes in energy expenditure and body composition after massive weight loss induced by gastric bypass surgery]