I want to dive into an important topic for anyone considering or currently using weight loss injectables: preserving muscle mass. These medications have been celebrated for their impressive contributions to weight loss but can come with a significant drawback: muscle loss. My goal is to help you understand why muscle preservation is essential and how we can work toward minimizing muscle loss during weight reduction.
Currently, there are three primary injectable medications for weight loss: Wegovy, Saxenda and ZepBound. These medications work by binding to the brain’s appetite-regulating centers, which reduces cravings, leads to early satiety and slows gastric emptying. This effect typically results in a consistent calorie deficit, which supports weight loss between 14.7% and 17.3% of total body weight within a year. However, part of this weight loss — often 20-40% — comes from lean muscle mass, not just fat.
Why muscle matters
Muscle, or lean body mass, is crucial for several reasons. It plays a key role in physical functioning, especially as we age since it supports mobility and strength. Losing muscle mass can decrease our strength and even increase the risk of falls — by around 20% for every 15% reduction in lower-leg strength. Muscle is also essential for insulin regulation, as it handles over 75% of insulin-mediated glucose disposal. Losing muscle mass can, therefore, increase insulin resistance, a risk factor for diabetes.
Muscle also influences metabolism. It significantly contributes to our resting energy expenditure (REE) — the calories burned by our body at rest, which makes up about two-thirds of our total daily energy expenditure. When we lose muscle, our REE drops, making it harder to maintain weight loss over time. Studies even suggest that lower body strength is linked to reduced mortality, meaning more muscle can support a longer, healthier life.
Supporting muscle preservation
To retain muscle while losing weight, we must focus on maintaining muscle protein synthesis (MPS), which is influenced by dietary protein and exercise. MPS must outweigh muscle protein breakdown to preserve muscle during weight loss.
Protein intake
Protein intake is foundational for muscle preservation. The general recommendation for protein intake is 0.8 grams per kilogram of body weight daily, but research suggests that a higher intake can be more beneficial, especially for those with a calorie deficit. Studies show that individuals aiming for muscle preservation should aim for about 1.2-1.6 grams per kilogram of body weight daily, which appears to support better muscle retention in both younger and older adults. Older adults may need even higher levels of protein due to the body’s decreased sensitivity to amino acids with age.
For those using weight loss injectables, ensuring adequate protein intake is essential, as muscle breakdown may increase due to the calorie deficit. For best results, try to consume 20-30 grams of high-quality protein per meal, which will help stimulate MPS. Including protein sources rich in leucine, an amino acid central to muscle building, can further support muscle maintenance. Supplements like whey protein, which is high in leucine, can be a convenient option if meeting protein needs through food alone is challenging.
Exercise for muscle maintenance
Exercise, especially resistance training, is one of the best ways to support muscle preservation. While aerobic exercise (like running or cycling) helps with overall cardiovascular health and can aid in weight loss, resistance training (like weightlifting) is particularly effective at preserving muscle. A combination of aerobic and resistance exercise three times per week — 30-40 minutes of each type — can optimize both weight loss and muscle preservation.
Studies have shown that those who incorporate resistance training in addition to a high-protein diet maintain better muscle mass during weight loss. Aerobic exercise alone may help with weight loss, but resistance training is key for strength preservation. Together, these forms of exercise improve not only muscle retention but also functional fitness and overall health.
In summary
Losing weight with injectables can be very effective, but it’s important to support muscle preservation along the way. Muscle is important for our quality and quantity of life, metabolism and overall health. By increasing protein intake and incorporating regular exercise — especially resistance training — we can help protect muscle mass as we work toward our weight loss goals.
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