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Weight Loss vs. Fat Loss: Lessons from “The Biggest Loser”

About a month ago, a new study on long-term weight loss and metabolism was published in the journal Obesity. Studies are published in scientific journals all the time with little, if any, public attention.

However, this one was different. This one was about former contestants on The Biggest Loser.

The study involved 14 of the show’s contestants and took a look at their body composition at three different times: before the show, after the show (after completing a 30-week weight loss program), and 6 years after the show. Strikingly, the Biggest Loser contestants had regained an average of 90 pounds after 6 years, nearly reversing all the incredible weight loss they achieved while on the show.

According to the study and the dozens of articles that reported on it, the reason for the weight gain was that the extreme weight loss had permanently throttled their metabolisms, meaning that in the 6 years following the show, when they were eating an amount of food they believed to be appropriate for their new body weights, they started gaining fat again.

Stories like this can make some people get discouraged and think negatively:

“See! Weight loss is impossible!” “If they can’t keep the weight off, even after they worked with professionals, how can I hope to keep it off?” “I’m just doomed to be fat and there’s nothing I can do about it!”

This is understandable: Seeing people regain their weight after achieving their goals in a very public setting can be extremely disheartening for people struggling to meet their own weight loss goals.

However, the unhappy result of the Biggest Loser contestants regaining their weight has one positive outcome: it underscores everything that is wrong with the way we think about improving health when we measure our results in terms of “weight loss” and not in terms of “fat loss.”

Don’t be discouraged by the doom and gloom you’re hearing about destroyed metabolisms and inevitable weight regain. Maintaining your weight loss is not impossible. There is a reason why the

Biggest Loser contestants failed to keep their weight off, and you can learn from their experience to ensure that it doesn’t happen to you.

What Happens When You Lose Weight

The first thing to understand is that when you lose weight, you’re generally not just losing body fat: you’re making changes to each component of your body composition. This includes, along with body fat, Lean Body Mass and Body Water. When you lose weight, you don’t necessarily get to control how much of each you lose (but you can have an influence on what’s lost – more on that later).

How does weight loss actually happen? While there are virtually hundreds of diets and exercise programs out there that will help you achieve fat loss – some better than others – the good ones boil down to essentially the same thing: reducing energy in from food while increasing energy out via exercise/activity (a caloric deficit) so that your body is forced to make up for the missing energy by breaking down your body tissues, including body fat.

While it would be awesome if you could just tell your body, “Hey! All that missing energy? Take it ALL from body fat, ok?”, that’s not what happens. As you lose weight, you will lose some muscle in the form of Lean Body Mass in addition to body fat.

Losses in Lean Body Mass must be avoided as much as possible, because the amount of Lean Body Mass you have directly influences the size of your Basal Metabolic Rate – what you probably are referring to as your “metabolism.”

Your Basal Metabolic Rate (BMR) is the number of calories your body naturally burns at rest. For example, a person with 142 pounds of Lean Body Mass begins the day with a need of 1761 calories already baked into their diet, and any activity they perform – even things as minute as walking, eating, or talking – adds to that daily caloric need.

More Lean Body Mass means a larger metabolism. Less Lean Body Mass means a smaller one.

This is the reason why professional athletes can eat north of 3,000 – 4,000 calories a day and not gain fat; in addition to all the calories they burn from playing sports, because they have a great deal of muscle mass, their bodies require more food just to maintain their form. It’s also why your skinny friend who can “eat anything and get away with it” might be able to: he or she may be fitter on the inside than you give them credit for.

So how does this apply to the Biggest Loser contestants?

Drastic Weight Loss = Muscle Loss and Smaller Metabolisms

It may come as a surprise, but obese individuals such as the Biggest Loser contestants actually have a lot of muscle. Here are a typical set of body composition results for someone who is severely obese.

While the weight and body fat bars are significantly over average, notice that the Skeletal Muscle Mass bar is as well. This is common for an obese person.

However, unlike an athlete, an obese person has developed this muscle by virtue of carrying a large amount of weight. Large amounts of muscle develop just to move such a heavy body around. What this means is that generally, obese people also have relatively large metabolisms.

The Biggest Loser contestants in the study lost an average of 128.5 pounds in 30 weeks, at a rate of about 4.3 pounds per week. That’s an incredible amount of weight to lose in such a short period of time, and is also an example of how a fixation on dramatic weight loss, and not fat loss, can have unintended negative consequences.

When the contestants lost all the weight, while they did lose a lot of fat, they also lost a lot of Lean Body Mass – 24.5 pounds of it on average – equalling 19% of their total weight loss. When almost 20% of your “weight loss” comes from muscle, it doesn’t sound as good, does it?

This muscle loss contributed to a drop in BMR from 2,607 calories to 1,996 calories. That’s a loss of 600 calories a day – almost an entire meal’s worth of calories, gone!

To a certain extent, this muscle loss was unavoidable. No one can reasonably expect to lose 39% of their total body weight in 30 weeks and not experience some form of muscle loss. Even bodybuilders – who also must dramatically transform their bodies when preparing for a competition – aren’t immune. In one study, a bodybuilder was able to drop his body fat percentage from 14.8% to 4.5% in 6 months in order to achieve a performance-ready physique.

Sounds great, but in terms of his raw weight loss, he too experienced 20% of his losses from Lean Body Mass.

For a bodybuilder in competition season, what matters the most is physical appearance, not optimal health. For that reason, temporary losses in Lean Body Mass (and metabolism) are acceptable for them.

By contrast, obese individuals often have much more important, health-related motivations for weight loss. Dramatic changes to Lean Body Mass and metabolism aren’t ideal, especially when the goal is to maintain a healthy body weight.

In fact, they can be downright catastrophic.

How Weight Regain Can Happen

6 years after the end of the competition, the Biggest Loser contestants had regained 83.6% of their fat loss. This was in large part due to the fact that their metabolisms never fully recovered to anything near their original levels. In fact, their metabolisms were recorded significantly lower than expected, even with the near complete regain of their Lean Body Mass.

Although the reason for this reduction in metabolism remains unclear, the author of the study speculate that it may have to do with a natural desire to counteract significant weight changes, leading them to advise keeping a close eye on metabolism when significant weight loss occurs.

One thing that applies generally, however, is a low metabolism, coupled with unregulated eating habits, is a sure-fire way to gain fat.

There’s also something worth pointing out. Although the Biggest Loser contestants were celebrated for their remarkable weight loss achievement in such a relatively short period of time, at the end of the competition, from a body compositional standpoint, they still had a lot of work left to do. Here’s what we mean:

  • The average percent body fat (PBF) dropped from 49.3% to 28.1%. This is a bit harder to interpret since the results lump the men and women’s PBFs together (and women naturally have higher PBFs), but when considering that the upper body fat percentage threshold for men is in the low 20s% range and women high 20s% to low 30s%, you can see that the contestants were still mostly overfat – on the verge of bringing themselves back into a healthy range, but not quite there yet.

Secondly, and arguably the most important failing:

  • Before the contest, the contestants had around 162 pounds of Lean Body Mass. Most of this was due to their extreme obesity. At the end of the show, they had an average of 142 pounds. After six years, this rose to 155 pounds: 7 pounds less than they started with.

Here’s the takeaway: given all this information we know about the contestants before, during, and after the competition, we can infer that the contestants were never in top shape, even at their lowest in terms of body weight. They almost got there, but not quite. They still had work to do.

Furthermore: The fact that the contestants had less Lean Body Mass than they did before they lost all their weight, yet regained almost all of their starting body fat, is a pretty strong indication that they weren’t trying to develop their muscles after the Biggest Loser.

If they were bench pressing and deadlifting for 6 consecutive years after the show, it would be quite unlikely that they would have regained the amount of weight they did. One might expect that they not only could regain all their Lean Body Mass, but even grow and develop their muscles beyond where they were before.

Without further development of Lean Body Mass and skeletal muscle to help grow the metabolism, weight regain remains a strong possibility if you aren’t extremely careful with the amount of calories you take in.

While the metabolisms of the contestants after 6 years were extraordinarily low, much lower than expected even when taking their Lean Body Mass into account, the fact remains that without efforts to develop muscle and Lean Body Mass and simply focusing on strictly weight loss, you run the risk of weight regain whenever you stop your exercise or diet.

How to Avoid Weight Regain

Here’s what we can learn from this unfortunate example of the Biggest Loser contestants’ weight regain.

1. A fixation on weight loss, and not body fat loss, is the wrong way to approach making positive health changes

Throw out tracking weight loss. You should be tracking changes in your body composition, which means optimizing your program for fat loss while minimizing Lean Body Mass loss. It’s not like this is impossible, either. Studies have shown that weight loss, when coupled with proper nutrition and strength training, can minimize and nearly eliminate Lean Body Mass loss.

To track body fat loss, you’ll need to have your body composition tracked regularly. There are a whole host of devices and methods for determining body composition, including callipers, hydrostatic weighing, DEXA, and BIA. If you want truly accurate results, always be tested by a highly skilled professional who uses a medical-grade tool to assess you. $10 plastic callipers and at-home bathroom scales aren’t going to be the best option.

2. Extreme diet/exercise programs have consequences

Here’s a good rule of thumb: if it sounds way too extreme, that’s because it probably is. The Biggest Loser contestants were losing more than 4 pounds of body weight per week, and that is extreme.

While it is true that obese individuals tend to lose body fat and body weight in general more quickly when they are introduced to a weight loss program, 4 pounds a week is a lot. You saw what happened: nearly 1/5 of their weight loss was important Lean Body Mass; you saw what that did to their metabolisms. Most dietary plans have you shooting for a ½ – 1 pound of fat loss per week, which is a manageable and sustainable goal that won’t cause such negative effects to metabolism.

3. If you want to keep the pounds off, pick up the weights

Many, many people have the idea that strength training/weight lifting is only for people who want to be huge or get giant muscles. Nothing could be further from the truth. Increased muscle has a whole host of benefits ranging from increased ability to recover from disease, reducing insulin resistance, helping you remain mobile as you age, and, of course, helping to combat obesity by increasing your BMR and metabolism.

A common fear is that increased muscle will make you look bulky and stop you from losing weight. Only one of those things is true. Muscle is significantly denser than fat, and a pound of muscle is much smaller than a pound of fat. If you were to theoretically replace 10 pounds of fat with 10 pounds of muscle and have a weight change of exactly zero, you would look much thinner, much leaner, and potentially have significant benefits to your health and wellness.

Hopefully you see that focusing on weight loss can lead to unfortunate consequences if you go about it the wrong way. By working out smarter and changing the way you view your health by finding out what your body composition numbers are, you’ll be on the path to getting fitter while keeping the fat off for good.

Yes, it might take longer than expected, but would you rather drop 100 pounds in less than a year, just to regain it all back, or would you rather spend the time to make small, impactful changes that lead to a lifetime of good health?

Thank you very much InBody USA for your contribution and publishing of this article. For more visit

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