Franziska Spritzler, RD, CDEMaintaining muscle mass is crucial for health, mobility, and metabolism, as age-related muscle loss increases the risk of frailty, osteoporosis, falls, and insulin resistance.(1) Preserving lean mass while losing weight is also crucial, as fat loss is often accompanied by muscle loss.(2)
Mounting evidence suggests that maintaining nutritional ketosis, aka euketonemia, may help preserve muscle mass and improve physical function during weight loss, although more research is needed to understand why.(3)
To support muscle preservation and growth on a ketogenic or low-carb diet, consider these five strategies:
1. Ensure Adequate Protein Intake
Protein is the main component of muscle. Studies suggest that older adults require more dietary protein to preserve muscle mass due to changes in metabolism and muscle protein synthesis.(4) Similarly, individuals who are losing weight can help offset muscle loss by increasing protein intake.(5)
How much protein do you need? In general, it’s best to aim for a minimum of 1.2 grams of protein per kilogram of ideal body weight daily and to spread protein intake across meals during the day.(4, 5) Learn more in our article Protein Basics for Thriving on a Ketogenic Diet.
2. Incorporate Strength Training and Resistance Exercise
While diet plays an important role in preserving muscle mass, physical activity is also essential. Strength training––such as weightlifting, bodyweight exercises (like squats and push-ups), and using resistance bands––can help stimulate muscle growth and prevent muscle loss during weight loss.(6) This type of activity has also been shown to increase muscle strength, reduce fat mass, and improve muscle performance in older adults with sarcopenia (severe age-related muscle loss).(7)
If you’re new to strength training or getting back into it after a break, begin with lighter weights and gradually increase resistance as your strength improves. Consider working with a professional to ensure safety and maximize results.
Learn more about strength training and other types of exercise in our article What Type of Exercise Is Best on a Low-Carb or Keto Diet?
3. Avoid a Large Caloric Deficit Over Time
Ketogenic diets have been shown to reduce appetite, resulting in a natural decrease in calorie intake.(8) Moreover, short-term very-low-calorie ketogenic diets appear to preserve muscle mass during weight loss.(9, 10) However, restricting calories over the long term increases the risk of muscle loss.(11) If you’re losing weight too quickly and notice muscle weakness or fatigue, it may be a sign that your calorie deficit is too large, and you should consider increasing your fat intake.
Learn more in our article What Is a Calorie Deficit and How Does It Help Weight Loss?
4. Prioritize Healthy Fats
While dietary protein is crucial for preserving muscle, dietary fat can influence hormone production. Hormones like testosterone and growth hormone support muscle growth and repair, and their levels naturally decline with age. Studies demonstrate that boosting fat intake may raise testosterone levels in men, resulting in better body composition when combined with weight training.(12) Moreover, in a large observational study, higher fat intake was linked to better muscle mass and strength in both young and middle-aged adults.(13)
Aim to get a variety of natural fats from foods: omega-3 fatty acids in fatty fish such as salmon, sardines, and mackerel); monounsaturated fats in meat, avocados, nuts, and seeds; and saturated fats in full-fat dairy products and other animal foods. For tips on the best fats to use in cooking and adding to meals, read our article The Best Butters and Oils for the Keto Diet.
5. Focus on Key Micronutrients
Along with adequate protein and fat intake, consuming foods or supplements rich in essential vitamins and minerals can support muscle preservation during weight loss and aging.
Micronutrients to prioritize include:
- Vitamin D: supports muscle strength and function, particularly in older adults.(14)
- Sources: Aside from fatty fish, most foods contain little to no vitamin D, so supplementation may be needed in the absence of frequent sun exposure. The general recommendation for vitamin D intake is 600 IU for most adults and 800 IU for those over 70, but many experts now suggest higher doses (eg 2,000 IU) to optimize blood levels.(15)
- Magnesium: assists in maintaining muscle quality with age.(16)
- Best keto dietary sources: Nuts, seeds, fatty fish, leafy greens, unsweetened chocolate
- Selenium: involved in muscle function; low levels are associated with sarcopenia.(17)
- Best keto dietary sources: Brazil nuts, seafood, meat, eggs
- B vitamins: plays a key role in building muscle; deficiencies may be linked to sarcopenia.(18)
- Best keto dietary sources: Meat, eggs, nuts, cheese, non-starchy vegetables
By prioritizing adequate protein intake, incorporating strength training, avoiding an excessive calorie deficit, and supporting overall health with healthy fats and key micronutrients, you can protect your muscle mass and enjoy the many benefits of a ketogenic or low-carb lifestyle.
References
- Sarcopenia and Its Implications for Metabolic Health, Journal of Obesity, 2019
- Proportion of Caloric Restriction-Induced Weight loss as Skeletal Muscle, Obesity, 2025
- Mitigating muscle loss during weight loss: can nutritional ketosis make a difference? A call for more research, Obesity, 2025
- Strategies to Prevent Sarcopenia in the Aging Process: Role of Protein Intake and Exercise, Nutrients, 2022
- The role of protein in weight loss and maintenance, The American Journal of Clinical Nutrition, 2015
- Resistance training effectiveness on body composition and body weight outcomes in individuals with overweight and obesity across the lifespan: A systematic review and meta-analysis, Obesity Reviews, 2022
- Effects of resistance training in healthy older people with sarcopenia: a systematic review and meta-analysis of randomized controlled trials, European Review of Aging and Physical Activity, 2021
- Do ketogenic diets really suppress appetite? A systematic review and meta-analysis, Obesity Reviews, 2015
- Very low calorie ketogenic diet combined with physical interval training for preserving muscle mass during weight loss in sarcopenic obesity: A pilot study, Frontiers in Nutrition, 2022
- Body Composition Changes After Very-Low-Calorie Ketogenic Diet in Obesity Evaluated by 3 Standardized Methods, The Journal of Clinical Endocrinology & Metabolism, 2016
- A Systematic Review and Meta-Analysis of the Effect of Caloric Restriction on Skeletal Muscle Mass in Individuals with, and without, Type 2 Diabetes, Nutrients, 2024
- Manipulation of Dietary Intake on Changes in Circulating Testosterone Concentrations, Nutrients, 2021
- Association of dietary fat intake with skeletal muscle mass and muscle strength in adults aged 20–59: NHANES 2011–2014, Frontiers in Nutrition, 2024
- Effects of Vitamin D on Muscle Function and Performance: A Review of Evidence from Randomized Controlled Trials, Therapeutic Advances in Chronic Disease, 2011
- Vitamin D Supplementation: A Review of the Evidence Arguing for a Daily Dose of 2000 International Units (50 µg) of Vitamin D for Adults in the General Population, Nutrients, 2024
- The Integral Role of Magnesium in Muscle Integrity and Aging: A Comprehensive Review, Nutrients, 2023
- Dietary selenium intake and sarcopenia in American adults, Frontiers in Nutrition, 2024
- Selected B vitamins and their possible link to the aetiology of age-related sarcopenia: relevance of UK dietary recommendations, Nutrition Research Reviews, 2018
