Yo-Yo Dieting Has An Unexpected Effect On Your Muscles

Weight loss can be frustrating. You did your part by setting goals, planning your meals, and keeping your willpower strong. You reached your goal weight, celebrated with friends, and bought new clothes to show off the "new" you. After a few months, you notice the weight gradually coming back. So you go back to your previously successful diet and return to your ideal weight.

The truth is, more than 50% of people who lose weight on a diet will gain it back within five years, according to a 2001 meta-analysis in the American Journal of Clinical Nutrition. Part of this reason is that your genetics, hormones, and behavior work together to establish a set point for your weight. Another reason is muscle loss. When you lose weight, you'll more than likely lose muscle as well. Muscle keeps your metabolism stoked, so you'll burn more calories at rest. When you gain weight again, the fat will return to your body more quickly than your muscle. Over time, yo-yo dieting can cause a gradual decline in overall muscle mass.

A 2019 study in Obesity looked at three groups of people whose average body mass index (BMI) was around 37. One group had one or no weight loss attempt, and another group cycled between two and five times. A severe weight cycling group had seen their weight cycle up and down more than six times. These yo-yo dieters had lower muscle mass and lower handgrip strength. They were also six times more likely to develop sarcopenia, which is a progressive muscle loss usually caused by aging.

Rapid weight loss from drugs like Ozempic can cause muscle loss because you're eating significantly less food. While a slower weight loss is more likely to burn fat for energy, a more drastic drop in weight each week could have your body breaking down muscle for energy. Losing muscle mass means you're also losing the stoking of your metabolism that muscle provides. A 2021 clinical trial in the New England Journal of Medicine found that although people who took Ozempic lost weight and lowered their risk of cardiometabolic conditions, some of the weight they lost was muscle.

If you're stuck on a cycle of yo-yo dieting, you could try a different approach to dieting rather than just restricting calories. A 2017 study in Medicine and Science in Sports and Exercise had three groups lose weight either by reducing their calories by 20%, reducing calories by 10% and exercising about 4 hours a week, or just exercising about 7 hours a week. Although all groups lost about 7% of their body weight, those who only dieted lost significantly more of their muscle compared to the other groups. The exercise group that didn't restrict their calories didn't lose any muscle.

Your workouts, combined with your diet, can work together to help you burn fat more efficiently. According to the International Sports Sciences Association (ISSA), you could burn more fat during low-intensity exercise, but high-intensity workouts will turn you into a calorie-burning machine after your workout as your body repairs and restores. On these days, refuel your body after your workout with protein and complex carbohydrates. Rather than doing high-intensity workouts every day, alternate between high- and low-intensity workouts. On low-intensity days, avoid simple carbohydrates and keep your total fat intake to 20% of your total calories.