Although the energy balance theory is pretty straight forward, it’s also highly variable from individual to individual, depending on the amount and quality of food consumed as well as activity levels. Many additional factors come into play to influence the rate at which you burn calories — age, sex, hormones, body composition, and family history, for instance. Now a straightforward theory is rather complex with a lot of moving parts.
Part of the equation that’s a bit harder to grasp, but is critically important, is the fact that when you reduce your calories, not only does your weight go down, so does your BMR. Following weight loss, energy balance re-establishes itself, but at a lower level. The new, thinner, you now requires approximately 10 to 15 percent fewer total calories than you needed before the weight loss just to maintain the new weight.
Think about that. You’ve achieved your goal of losing 20 pounds. But now that you’re at your ideal weight, you have to continue eating less than you did before your diet just to maintain your new weight. There’s less of you now. You simply don’t need as many calories. Most people, though, resume eating pre-weight-loss amounts of calories, so weight is slowly regained.
When it comes to weight loss, your body’s not your friend
Although our responses to weight loss efforts are highly individual, it appears that in general our bodies are better equipped to defend against weight loss than avoid weight gain. It’s thought this is an evolutionary hold-over from when humans had to hunt for food. In fact, some research shows that our bodies have built-in mechanisms to compensate for efforts to lose weight, for example adaptive thermogenesis, which many dieters experience when they “plateau.” Basically, your body thinks it’s starving, so it starts burning muscle instead of fat.
When consuming fewer than normal calories, people also naturally experience a dip in energy and may become less active, driving down TDEE. Additionally, there is evidence that people who exercise regularly also often reduce their non-exercise physical activity, essentially nullifying the effort. Further, in addition to the physiologic effects of exercise, some people may also experience a psychological component — it’s the voice in your head that says “feel free to eat more as a reward for your effort.”
More studies are needed to understand the many factors that influence energy balance, but in general, it appears that reducing the calories you consume is associated with a reduction in the calories you burn, which, at least partially, offsets the dietary-induced energy deficit. Understanding that achieving and maintaining weight loss is more complicated than simply reducing calories and increasing activity can help when you are devising a weight-loss strategy.
So it is possible to lose weight without exercise, but if your motivation for doing so is to improve your health, adding activity can make it easier to achieve your goal, but also has many health benefits of its own. More than two-thirds of Americans over the age of 20 are overweight, according to the Centers for Disease Control and Prevention (CDC). Of those, nearly 40 percent are obese. And the problem isn’t confined to adults. Just over 20 percent of 12- to 19-year-olds and just over 17 percent of 6- to 11-year-olds are also obese, according to the CDC. Clearly, strategies to successfully address the obesity epidemic are needed.
April 09, 2020
Janet O’Dell, RN