Why Does Weight Loss Slow Down Over Time?
Monica Reinagel, MS, LD/N, CNS
A recent study found that dieters lose weight more quickly at the beginning of their diets. Even when they stick to their diets, the rate of weight loss slows down over time. (Most of us didn’t need a big medical center study to tell us that.)
The headlines claim that this “study questions the ‘calories in, calories out’ equation for body weight.” Really? There’s actually a pretty simple explanation for this well-known phenomenon — one that doesn’t require us to abandon the First Law of Thermodynamics.
The Basics of Weight Loss
In order to lose weight, you need to eat fewer calories than your body burns every day — creating what we call a “calorie deficit.” The size of the calorie deficit determines the pace of weight loss. In round numbers, if you create a calorie deficit of 500 calories a day, you can expect to lose about one pound a week. But as you lose weight, your calorie requirements go down because a smaller body needs fewer calories. If you keep on eating the same number of calories every day, the size of your calorie deficit will slowly shrink and the pace of weight loss will slow.
In order to continue to lose weight at the same pace over the course of a major weight loss, you’d need to eat fewer and fewer calories as you lost weight. (Note: I don’t actually recommend this. See why below.)
Other Factors that Affect Calorie Deficit
Of course, there are a few complicating factors. Over time, dieting can slow your metabolism, causing you to burn even fewer calories and shrinking that calorie deficit even more. (See “How to Break Through a Weight Loss Plateau” for tips on how to deal with this.)
On the other hand, there are some things you can do to expand — or at least maintain — that calorie deficit without eating less. Physical activity — whether it’s going to the gym or simply taking the stairs at work — increases the number of calories burned every day. And activities that build lean muscle mass, such as strength training, also help you burn more calories even at rest.
Regardless of how you manipulate it (eating less, exercising more, calorie cycling, building muscle), the size of the calorie deficit is still the primary factor in the speed of weight loss.
Slow Weight Loss is a Good Thing
Although it may be frustrating, losing weight slowly is actually not a bad thing — especially at the tail end of a significant reduction. It allows you to make a gradual transition (both mentally and physically) into your long-term maintenance phase. And that greatly increases your chances of maintaining a healthy weight for the long term.
Have you had success losing weight and keeping it off? What was the key for you?
Weight Loss image courtesy of Shutterstock
About the Author
Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes’ most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation’s leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.