The Biggest Loser: Metabolism Buster?

  • 4 Minutes Read

Six years after the show, many Biggest Loser contestants have regained weight. A new study suggests the reason is permanently lowered metabolic rate. Is the Biggest Loser weight loss plan a failure?

The Biggest Loser: Metabolism Buster?

Take several severely obese people, put them in a TV weight loss boot camp for 30 weeks and force them to lose lots of weight. Pick a winner, say goodbye and send everyone back to their normal lives. Lives that don't involve drill marshal compulsory work outs all day long, interspersed with small ready-to-eat low calorie meals. Lives that instead involve jobs, commuting, parenting, friends, chores and commitments. The lives that made them obese in the first place.

This is The Biggest Loser. Six years after the first 16 contestants completed the show, some obesity researchers decided it would be interesting to see how those people were doing weight-wise. What they found was quite discouraging. Of the 14 who agreed to participate in this study, most had regained significant weight; 5 were right back at their pre-show weight. The researchers wanted to investigate why this happened, so they took dozens of measurements, including metabolic rate and energy expenditure, using sophisticated techniques.

Full Disclosure: I do not watch The Biggest Loser. It just doesn't interest me. I think it exploits desperate people. Nevertheless, it's a phenomenon and lots of people do watch it. And many people participate. They're put into a 24/7 weight loss fish bowl for a few weeks. They're given all kinds of support. That alone would be motivation to stick to a plan. Actually if you're in the program, you have no option but to stick to the plan.

No surprise: when you stick to that plan, it works. People lose weight, some more quickly than others, but they lose weight. It's not a miracle, or a magical effect of some fad diet. It's plain old Eat Less Exercise More.

The problem for some health professionals is that weight loss on The Biggest Loser happens too fast. According to this study of Biggest Losers 6 years later, average weight loss during the show was 2-6 lbs per week for 30 weeks. That's an extreme rate of weight loss, even if it is averaged over 30 weeks. 6 lbs? Do the calorie math: it means a 3000 calorie deficit per day. Granted, at first a lot of the weight loss is water, but even then it's mind-boggling. Even if you ate nothing, the only way to accomplish weight loss close to that is with a whole lot of daily exercise. And the participants did not eat nothing. The finding that got the most media attention had to do with energy expenditure. According to the measurements, metabolic rate was significantly reduced compared to what it was pre-show/pre-weight loss.

Let's think about this. The BL participants' daily energy requirements at the beginning of the program were high, because they were large people. As they lost weight, their energy requirements decreased. No surprise; their bodies were getting smaller and needed less energy. Presenting this drop in calorie needs as some aberration is incorrect. It's to be expected; it's normal. You lose weight, you are smaller, and you need fewer calories.

What surprised the researchers, based on their assessments at 6 years, is that despite significant weigh regain, daily calorie requirements were lower than expected. According to the study data, the Resting Metabolic Rate at the end of the show was an average of almost 2000 calories per day. At the 6 year follow up, it was around 1900 calories per day, even though people had gained an average of close to 90 lbs. Adding that weight should have boosted RMR, but it didn't. In other words, people seemed to be getting by on fewer calories than in the past. Making it really easy to regain weight.

And in fact, this 6-year follow up study showed that the 14 people who participated in the evaluation had regained weight, to varying degrees. So is The Biggest Loser plan a failure? Or does the study have flaws? Let's consider the flaws.

There were only 14 study subjects. Obviously the researchers were working with a limited population, but data from only 14 people doesn't produce great statistics.

Everyone's data was lumped together. Why? As the researchers note, one person did not regain significant weight at all. Five regained all the weight. That leaves 8 people who regained some degree of weight, but not all that they'd lost. But if you average the 14 people together it all looks pretty bad.

What was going on for the 6 years between TV show and follow up study? Did everyone religiously stick to the exact diet and fitness regimen from the show for 6 years, with no support system, while living their normal lives (see above: jobs, commuting, parenting, family, etc.). I doubt it. And that's probably the biggest problem with The Biggest Loser in my book. After 30 weeks living in an intense support system, how do people suddenly manage on their own? It would be extremely difficult, if not impossible. So it's not hard to imagine things slipping back to the obesogenic lifestyle of the past: a little too much food, not much physical activity, food that's not so healthy. Gradually the weight creeps back on.

I'm not sure what to make of the fact that metabolic rate remained low. In fact, total energy expenditure (measured by a technique called Doubly Labeled Water) did go back up somewhat at the 6 year mark, corresponding somewhat to the weight regain. Bigger body = more energy used.

What do I think?

  1. I'd like to see data for each of those 14 people presented separately, not lumped together. What about the person who didn't regain? What were that person's measurements? How did that person do it? What's different between the 5 who regained everything and the other 8 who regained varying amounts of weight?
  2. I'd like to see data on food intake for the intervening 6 years. I highly doubt that those people were sticking 100% to their saintly low calorie Biggest Loser diet for 6 years and strangely gained back a lot of weight.
  3. I'd also like to see data on actual physical activity for those 6 years.

Is the Biggest Loser plan a bad idea?

Like I said, I'm not a fan of the concept. I think it gives everyone else the wrong idea about what a realistic weight loss plan looks like. Non-contestants think extremely fast weight loss is reasonable, and they get frustrated when it doesn't happen in the real world.

And, as this study suggests, there might be some longer-lasting effects of such rapid weight loss on metabolic rate. Meaning, if you want to keep that weight off, you have to be extra vigilant about what you eat every single day and how much you exercise every single day. Most people can't keep up with that kind of dedication. They don't have the time or mental energy. There are too many temptations to indulge in too much food and avoid exercising.


Maintaining weight loss is probably more difficult than losing it in the first place. And that's true for everyone, whether you lost weight quickly on national TV or slowly, on your own. But here's the message I don't want people to take away from this gloomy study: that it's pointless to lose weight. That's a terrible message. Losing excess weight can have a beneficial impact on disease risk and quality of life. Just know that you aren't "cured" when you reach your goal weight. You can't go back to your previous habits and expect the weight to stay off.

Weight Loss->Biggest Loser
May 24, 2016
Donna P Feldman MS RDN is author of Food Wisdom for Women and "Feed Your Vegetarian Teen". She writes about food and nutrition at Radio Nutrition.

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