Losing Fat While Protecting Muscle
When people want to lose weight, they usually want to lose body fat. But weight loss can also include lean tissue. Lean tissue includes muscle, water, bone, and organs, so a drop in lean mass does not necessarily mean the same amount of muscle was lost.
Keeping muscle matters for strength, balance, and staying active as we age. Research suggests that two habits can help during weight loss: eating enough protein and doing exercises that challenge the muscles.
Eat Enough Protein
A review of 47 randomized trials involving 3,218 adults with overweight or obesity examined whether higher protein intake helps protect muscle during weight loss. Among the 28 trials that measured muscle mass, higher protein intake helped limit muscle loss (1).
The review suggested that more than 1.3 grams of protein per kilogram of body weight daily may help maintain or increase muscle mass, while less than 1.0 g/kg/day was linked to a greater risk of muscle loss. However, higher protein intake did not consistently protect strength or physical function. Study quality varied, so these amounts are guides rather than precise cutoffs (1).
For many generally healthy adults trying to lose weight, about 1.2–1.6 grams of protein per kilogram of body weight daily may be a practical range (2). For someone weighing 150 pounds (68 kilograms), that is approximately 82–109 grams a day. Individual needs vary, and more protein is not always better.
Try including protein at each meal. Common servings provide approximately:
• Fish: 19–23 grams per 3 ounces cooked
• Eggs: 6 grams per large egg
• Plain Greek yogurt: 17 grams per 6-ounce container
• Firm tofu: 10–15 grams per ½ cup
• Soy milk: 7–8 grams per cup
• Cooked beans: 7–8 grams per ½ cup
• Cooked lentils: 9 grams per ½ cup
• Chicken or turkey breast: 25–26 grams per 3 ounces cooked
• Lean beef: 22–26 grams per 3 ounces cooked
Amounts vary by product and preparation, especially for tofu and yogurt. Check the package label for a more exact number. Protein powders can be convenient, but they are not necessary.
Give Your Muscles a Reason to Stay
Strength training, also called resistance exercise, makes muscles work against a load. Examples include lifting weights, using resistance bands, and doing squats or wall push-ups.
A review of 25 randomized trials compared dieting plus strength training with dieting alone in adults aged 18–65 with overweight or obesity. Total weight loss was similar, but adding strength training helped participants lose more fat, preserve more lean tissue, and gain more strength (3).
This shows why the scale cannot tell the whole story: two people may lose the same amount of weight but differ in how much comes from fat versus lean tissue.
What Studies in Older Adults Show
Losing weight can help older adults with obesity move more easily, but it can also reduce muscle and bone mass. A six-month randomized trial of 160 older adults compared a reduced-calorie diet combined with aerobic exercise, strength training, or both. A control group received neither the weight-management nor exercise program (4).
The three exercise groups lost about 9% of their body weight, but their results differed:
• Everyday physical tasks improved by 21% with combined exercise, compared with 14% with either exercise type alone.
• Cardiovascular fitness improved by 17% with combined exercise and 18% with aerobic exercise, compared with 8% with strength training.
• Muscle strength increased by 18% with combined exercise and 19% with strength training, compared with 4% with aerobic exercise.
Strength training also helped limit lean tissue loss. Lean tissue declined by 2% with strength training, 3% with combined exercise, and 5% with aerobic exercise. Hip bone density declined by 0.5%, 1%, and 3%, respectively. These findings suggest that combining both exercise types offers the broadest benefits, while including strength training helps protect lean tissue and bone (4).
A further analysis of the same trial examined fat between muscles and around internal organs. Combined exercise reduced these fat deposits by 41% and 36%, respectively—more than either exercise type alone. The body's response to insulin improved by 86% with combined exercise, compared with 50% with aerobic exercise and 39% with strength training (5).
Extra protein does not always produce additional benefits. In a separate 10-week trial, 100 adults aged 55–80 followed reduced-calorie diets with higher or normal protein intake, with or without strength training three times a week. Actual protein intake averaged 1.13 versus 0.98 g/kg/day—a smaller difference than planned (6).
The higher-protein plus strength-training group gained 0.6 kg (1.3 lb) of fat-free mass compared with its starting level. However, it did not show a statistically significant advantage over the other groups. The small difference in protein intake limits what this study can tell us about the benefits of extra protein (6).
Time-Restricted Eating: The Type of Weight Lost Matters
An eight-week randomized trial of 54 college students with overweight or obesity compared eating within a 10-hour daily window, strength training, both approaches, or maintaining their usual lifestyle (7).
Time-restricted eating, alone or combined with strength training, reduced body weight by more than 2 kg (4.4 lb). However, body composition changed differently:
• Time-restricted eating alone: Fat-free mass fell by 2.3 kg, with no significant fat loss.
• Strength training alone: Fat mass fell by 1.1 kg, while fat-free mass increased by 1.6 kg.
• The combined approach: Fat mass fell by 3.2 kg, while fat-free mass was maintained.
This small, short-term study suggests that adding strength training to time-restricted eating may help young adults lose fat while preserving fat-free mass. Changes in fat-free mass should not be interpreted as changes in muscle alone (7).
Keep the Plan Manageable
Aim for a moderate calorie reduction that you can maintain, with enough food to support exercise and recovery. Walking, cycling, and other aerobic activities support heart health; adding strength training helps preserve strength.
Look beyond the scale. A smaller waist, better clothing fit, and improved strength can be useful signs of progress, even when weight changes slowly.
The goal is to lose excess fat while keeping as much strength and function as possible. Enough protein, regular strength training, and a sustainable eating plan work together toward that goal.
If you have kidney disease or another condition that affects your protein needs, ask your healthcare professional before substantially changing your intake.
References:
1. Kokura Y, Ueshima J, Saino Y, Maeda K. Enhanced protein intake on maintaining muscle mass, strength, and physical function in adults with overweight/obesity: a systematic review and meta-analysis. Clin Nutr ESPEN. 2024;63:417–426.
2. Leidy HJ, Clifton PM, Astrup A, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015;101(6):1320S–1329S. doi:10.3945/ajcn.114.084038.
3. Binmahfoz A, et al. Effect of resistance exercise on body composition, muscle strength and cardiometabolic health during dietary weight loss in people living with overweight or obesity: a systematic review and meta-analysis. BMJ Open Sport Exerc Med. 2025;11(3):e002363. doi:10.1136/bmjsem-2024-002363.
4. Villareal DT, et al. Aerobic or resistance exercise, or both, in dieting obese older adults. N Engl J Med. 2017;376:1943–1955. doi:10.1056/NEJMoa1616338.
5. Waters DL, Aguirre L, Gurney B, et al. Effect of aerobic or resistance exercise, or both, on intermuscular and visceral fat and physical and metabolic function in older adults with obesity while dieting. J Gerontol A Biol Sci Med Sci. 2022;77(1):131–139. doi:10.1093/gerona/glab111.
6. Verreijen AM, Engberink MF, Memelink RG, et al. Effect of a high protein diet and/or resistance exercise on the preservation of fat free mass during weight loss in overweight and obese older adults: a randomized controlled trial. Nutr J. 2017;16(1):10. doi:10.1186/s12937-017-0229-6.
7. Cui T, Sun Y, Ye W, Liu Y, Korivi M. Efficacy of time restricted eating and resistance training on body composition and mood profiles among young adults with overweight/obesity: a randomized controlled trial. J Int Soc Sports Nutr. 2025;22(1):2481127. doi:10.1080/15502783.2025.2481127.
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