Losing weight is difficult for some people and keeping it off is even harder. More than 80% of people who lose more than 10% of their body weight gain it back and often more. The reason? It’s partially due to a phenomenon called metabolic compensation. Metabolic compensation describes how your body responds to weight loss.
You probably think of weight loss in terms of calories – consume more calories than you burn off and you’ll gain weight. Burn more calories than you take in and the pounds will drop off. It makes sense thermodynamically but your body has sneaky ways of quietly adapting to calorie restriction. You see, your body’s job is to make sure you have enough energy for survival. It doesn’t care how you look in a pair of jeans or a swimsuit. When you provide it with too few calories consistently, it compensates by slowing things down and by becoming more efficient at using the fuel you’re providing it with.
How Your Body Compensates for Weight Loss
What causes your body to behave this way? Some of the compensation arises from changes in key hormones that regulate metabolism and appetite, particularly leptin. As you might know, leptin is a hormone that signals the hypothalamus in your brain that fat stores are sufficient and you don’t need extra stored fat. It signals the brain to cut back your appetite and speed up your metabolic rate. When you cut your calorie intake, leptin levels drop, your metabolism slows, and your appetite increases.
Another way your body compensates for calorie restriction and weight loss is the effect it has on your muscles. Your muscles become more efficient when you move so that you burn fewer calories. Plus, as you lose weight, you burn fewer calories during exercise because your body weighs less. Have you ever noticed how exercise machines ask for your weight to measure the calories you burn during exercise? That’s because you burn fewer calories when you weigh less and more when you’re heftier. But, that’s not the full story. Your muscles become more efficient in response to weight loss as well. So, you burn fewer calories with exercise and with all movement. Many people fail to adjust their dietary habits with these adaptations and gain all of the weight back.
Not surprisingly, the master metabolism regulator, your thyroid also compensates for weight loss. The active form of thyroid hormone is called T3. A study showed that even modest weight loss leads to a decreased conversion of the less active form of thyroid hormone, T4, to the active form. The result is a slowing of resting metabolism rate.
As you can see, dropping your calorie count too low can actually make it harder to lose weight and to maintain the weight that you lose. However, there is a theoretical plus side. Slowing your metabolic rate can, based on some studies, reduce oxidative damage to cells and tissues and, potentially, slow the aging process. Most of the research showing this has been in animals. However, if your focus is on losing weight, dropping your calorie intake too low is counterproductive.
Ways to Reduce Metabolic Compensation
Fortunately, there are some things you can do to reduce the amount of metabolic compensation your body experiences and, hopefully, increasing the odds that any weight you lose you can maintain. Let’s look at some of them.
Resistance Train
When you lose weight, you lose both body fat and muscle. Muscle is more metabolically active than fat and contributes more to your resting metabolic rate. Having more muscle boosts your metabolism and helps offset the metabolic slowdown you get with weight loss. In an attempt to lose weight, some people ramp up the time they spend doing cardio. Focusing too much on cardio in combination with calorie restriction leads to greater loss of muscle tissue. However, if you devote a high proportion of your time to resistance training, you’ll experience less loss of muscle tissue and can actually increase the total amount of muscle you have on your frame. You need that extra muscle to prime your metabolism and burn more calories with exercise and at rest. Aerobic exercise may burn calories but it can actually worsen the metabolic compensation you experience when you’re trying to lose weight.
Boost Your Protein Intake
Protein not only boosts satiety, helping you be satisfied with less food intake, it also protects against muscle loss. In a 2010 study carried out on healthy athletes, those that ate a diet consisting of 35 grams of protein lost less muscle tissue than those who ate a diet composed of 15% protein. Modestly increasing the protein content of your diet helps protect against muscle loss that can further slow your metabolism.
Cycle Your Calories
Your body compensates more when you consistently lower your calorie intake. You can offset this by cycling the calories you take in each day. For example, reduce your calorie intake for 3 or 4 days and then raise it back to baseline for a day or two. During the 3 or 4 days of calorie restriction, your leptin level drops. The reduction in leptin slows your resting metabolic rate and increases hunger. By taking your calories back to maintenance for a day or two, your leptin level rises again. In turn, your metabolism speeds back up and your appetite declines.
The Bottom Line
Losing weight and maintaining it is tricky, primarily because your body fights your efforts. However, there are things you can do to mitigate these changes and now you know three of them. Most importantly, don’t try to lose weight too quickly – and don’t forget weight training is part of the equation.
References:
Antioxid Redox Signal. 2011 Jan 15; 14(2): 275–287. doi: 10.1089/ars.2010.3253.
MetabolicEffect.com. “How to Maintain Weight Loss and Beat Weight Loss Resistance”
Med Sci Sports Exerc. 2010 Feb;42(2):326-37. doi: 10.1249/MSS.0b013e3181b2ef8e.
The New York Times. “Metabolism Found to Adjust For a Body’s Natural Weight”
Thyroid. 2014 Jan 1; 24(1): 19–26. doi: 10.1089/thy.2013.0055.
Clin Endocrinol (Oxf). 2003 Aug;59(2):258-62.
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