You lose more than fat when you diet

Did you know that when you shed pounds, you lose something else?

“You lose fat, you lose muscle also,” confirmed family practitioner Arash P. Tadbiri, MD, of Bourne Primary Care, who is board certified in geriatrics.

Just how much lean muscle you lose varies, and your age and condition determine whether the loss may be a concern. Luckily, there are ways to limit the loss.

How Much Muscle Might You Lose?

If you shed pounds the most common way – by dieting – and you’re overweight or obese, you can expect about 20-30 percent of the weight loss to be lean tissue, according to a May 2017 article in Advances in Nutrition. People with a healthier body weight tend to lose more lean tissue; around 35 percent. In general, men tend to lose more muscle mass through dieting. Obese people tend to have more muscle mass than thinner people, but it is in poorer condition.

Muscle loss has recently been raised as a possible concerning side effect of popular drugs used for type 2 diabetes and weight loss including Ozempic, Wegovy (both semaglutide) and Mounjaro (tirzepatide) that work like a hormone called GLP-1 (glucagon-like peptide 1), noted an October 2023 article in Scientific American.

A clinical trial of semaglutide found that over 68 weeks, participants each lost an average of 23 pounds of fat and 15 pounds of lean muscle, according to a September 2023 Fortune Well article. The 140 participants had a mean age of 52.

How to Limit Muscle Loss

A July 2021 article in Nutrients said among the groups most likely to be adversely affected by muscle loss that accompanies weight loss are:

• Elderly people
• Post-menopausal women
• People with metabolic disease
• Athletes

Exercise and increased consumption of protein can limit muscle loss. Extra protein is especially recommended for elderly adults, who, despite having a lower need for calories, experience progressive muscle loss as part of aging – a process called sarcopenia. According to the federal Office on Women’s Health, adults over 30 lose about 3-5 percent of their muscle every 10 years. Loss of muscle can lead to less strength and function, resulting in falls and disability. It may also contribute to development of diabetes, cardiovascular disease and obesity.

While eating more protein might benefit older adults, the U.S. Office of Disease Prevention and Health Promotion says most don’t eat enough, particularly Americans 71 and older. Older bodies require more protein because they don’t process essential amino acids from protein as well as younger people. The federal RDA (Recommended Daily Allowance) for protein for all adults is 0.8 grams per kilogram of weight (about 2.2 pounds), which some experts consider too low for older adults.

For obese people who are dieting to lose weight, the research review in Advances in Nutrition concluded:

• Eating a high-protein diet can help keep muscle mass, but alone doesn’t boost strength.
• Exercise, particularly resistance exercise, can both maintain muscle and add strength.

“Exercise is very important. More important than diet for elderly adults,” Dr. Tadbiri said.

Exercise is commonly recommended to treat sarcopenia. A meta-analysis of 42 trials involving 3,728 people with sarcopenia and a mean age of 73 found resistance training, alone or with aerobic and balance exercises, worked best to improve strength and ability. The researchers found nutritional counseling with exercise improved results for grip strength and other functions more than exercise alone. The article was published in June 2023 in the Journal of Cachexia, Sarcopenia and Muscle.

Who Should Use Weight-Loss Drugs?

Regarding the surging interest in new weight-loss drugs, Dr. Tadbiri said he takes a conservative approach, especially for his older patients, as it raises issues of possible drug interactions. Plus, older people tend to have more chronic illnesses.

“I would consider adding weight-loss medication to obese patients with comorbidities, based on pros and cons,” he said. “It’s not just because of weight, but also because of improving comorbidities.”

Dr. Tadbiri said he would be more inclined to prescribe one of these drugs “if a patient is 400 pounds, has diabetes, COPD,” than for a patient with no chronic conditions other than excess weight.

He also said patients would have to be willing to make lifestyle changes, not just take the medicine.