Does "yo-yo dieting" permanently destroy your metabolism? It's a question researchers have been asking for decades. This month, the journal Obesity published research, suggesting that metabolism is permanently damaged by dieting. Researchers followed 14 "Biggest Loser" contestants to see if their bodies burned more or fewer calories than would be expected after losing weight. They did a test, called RMR or Resting Metabolic Rate, at the end of the 30 week competition and again 6 years later to find out whether the competitors' metabolisms became sluggish after losing so much weight. And, they wanted to know if the metabolic rate would ever recover...
While the study was not perfect, it provided some interesting results worth discussing.
- Dieting Slows Metabolism: The lower your body weight, the lower your metabolic rate (generally speaking). So as a person's weight goes down, so does their RMR. But, in this case, the competitors' RMRs went even lower than what would be expected based on their new lower weight. It may be that the extreme nature and severity of calorie restriction used on the Biggest Loser was particularly metabolism-destroying. It may be that group of people was metabolically unlucky (they were not a random sample of the population).
- Maintaining Weight Loss is VERY Challenging: After 6 years, 13 of 14 Biggest Loser contestants regained weight. Five of those almost made it back to their starting weight or went higher on the scale. Other published research suggests that 6 years after losing weight, only 6% of people maintain a weight loss of 5%. Five percent is enough of a weight loss to improve blood pressure, blood sugar, etc., but it's not the degree of weight loss that a typical dieter would deem "successful." Five percent of 200 pounds is just 10 pounds. The average weight loss for these Biggest Loser competitors was 39% at the end of that season. Only 7% of them kept the weight off after 6 years.
- Re-gaining Weight Doesn't mean Re-gaining a Faster Metabolism: Even though people re-gained the weight, they did not re-gain the higher metabolic rate they started with. To put it another way, at the end of the show, the average weight was 90.6 kilograms, with an average RMR of 1,996 kcal/day. Six years later, the average weight went up to 131.6 kilograms, with an average RMR going down to 1,903 kcal/day. As people gained weight, their metabolism should have gotten faster. But, it didn't. And the discrepancy couldn't be explained away due to age, muscle mass or anything else the researchers looked at. Other published research has shown that metabolism does return to it's expected rate. Several other published studies have had conflicting results, suggesting that metabolism does recover...so the jury is still out on this one!
- The more intensive and holistic a weight loss program it is, the more successful people are at losing weight and keeping it off. The Biggest Loser contestants had an intense few months on the Biggest Loser Ranch, and while they learned to exercise and eat less in that setting, they didn't have ongoing support once they returned to their normal lives. In an intensive diabetes prevention program called Look AHEAD, people who received group therapy, behavior weight loss counseling and follow up for 8 years. They received more support and assistance than just about any weight loss program out there. With all of the ongoing education, support and follow up, 27% of them maintained a 10% weight loss after 8 years. And even though that doesn't sound like success to most people hoping to lose weight, it is one of the most successful trials to date. Even gastric bypass patients, who get minimal follow up with a dietitian or weight counselor, regain the weight.
- Preventing weight gain is the best way to go. While it may be too late for 67% of the adult US population to prevent themselves from being overweight or obese, it is never too late to prevent further weight gain. And, the idea of just keeping overweight individuals from gaining weight, rather than prescribing weight loss, is an idea that is gaining some traction with obesity researchers. For people who are committed to losing weight, making realistic, sustainable changes in eating and exercise habits over time may be the best course of action.
- Focus on Behavior & Habits. Set clear, actionable, realistic food & exercise goals for yourself each day, week or month. Master a new habit, then create another healthy habit, then another. And, if you really want success, seek support. Whether you have a coach, dietitian, support group, hospital-based education and support program or just a really strong buddy-system, having ongoing support will make you more successful in the long run.
- Eat for Health. Your motivating force needs to be deeper than the desire to be thin. In fact, you may decide that your goal is just to NOT gain weight. Dig in and get very clear about why you want to eat better and move more. Are you prediabetic? Would you like to avoid medications? Do you have kids, grand-kids or a bucket list to check off? A compelling reason I often hear from the wonderful people in my classes is that they'd like to be able to sit on the floor and play with their grandchildren. And, they'd like to be able to get back up too!
- Get More NEAT. Move more throughout every day vs starting a big exercise program that isn't sustainable. NEAT is lifestyle activity (Non-Exercise Activity Thermogenesis). Move around more during every day, take the stairs, park in the back 40, dance around the house, and sit less throughout the day.
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