To maintain muscle, most people need to eat at or near their total daily energy expenditure, which typically falls between 14 and 18 calories per pound of body weight depending on how active you are. Dropping below that number, even modestly, triggers your body to start breaking down muscle tissue for energy. But calories alone aren’t the full picture. Protein intake, training, and even your age all shift what “enough” actually looks like.
How to Find Your Maintenance Calories
Your total daily energy expenditure has three components: your resting metabolism (the calories your body burns just to keep you alive), the energy you burn through physical activity, and the thermic effect of food, which accounts for roughly 10% of your total intake. Of these three, physical activity is the most variable and the one you have the most control over.
A common way to estimate your maintenance calories is to multiply your resting metabolic rate by a physical activity level (PAL) factor. Someone who is mostly sedentary might have a PAL of around 1.4 to 1.5, meaning their total daily burn is about 1.4 to 1.5 times their resting rate. Someone who exercises regularly tends to land closer to 1.7 to 1.75, which is roughly equivalent to 60 to 90 minutes of moderate activity like walking each day, or 30 to 45 minutes of vigorous activity like running.
For a practical starting point, take your body weight in pounds and multiply by 15. A 180-pound person would start around 2,700 calories per day. Track your weight for two weeks. If it stays stable, you’ve found your maintenance range. If you’re losing, add 200 to 300 calories. If you’re gaining, subtract the same amount. Online TDEE calculators can give you a more personalized estimate using your age, height, sex, and activity level, but real-world tracking is always the best calibration tool.
Why Eating Below Maintenance Costs You Muscle
When you eat fewer calories than your body needs, it has to get that energy from somewhere. A deficit of 30 to 40% below maintenance suppresses your body’s ability to build new muscle protein after meals. This happens quickly, within just two to three weeks of sustained restriction. Interestingly, a more moderate and prolonged deficit can actually increase muscle protein synthesis rates, but muscle loss still occurs because the body simultaneously ramps up muscle protein breakdown. The net effect is less muscle over time.
This is why aggressive dieting is particularly risky for muscle. The larger the deficit, the faster your body turns to muscle tissue as fuel. Adequate protein can slow this process, but it can’t fully stop it when the calorie gap is too wide. If your goal is to keep the muscle you’ve built, eating at or very close to maintenance is the safest approach.
How Metabolic Adaptation Changes the Target
If you’ve recently lost weight, your maintenance calories are likely lower than a formula would predict. This phenomenon, called adaptive thermogenesis, means your body becomes more energy-efficient after a period of dieting. Studies have measured this gap at roughly 90 to 250 fewer calories per day than expected, and it can persist for months or even years after weight loss.
Most of this metabolic slowdown happens outside of your resting metabolism. It shows up in the non-resting portion of your daily energy expenditure: you move less without realizing it, fidget less, and your body extracts slightly more energy from food. For someone who has dieted down and wants to maintain muscle at their new weight, this means your true maintenance number could be 100 to 250 calories lower than what a calculator tells you. Tracking your weight and adjusting is especially important if you’ve come off a cut.
Protein Is the Most Important Macronutrient
Calories set the stage, but protein does the heavy lifting when it comes to preserving muscle. The International Society of Sports Nutrition recommends that people who exercise regularly consume 1.4 to 2.0 grams of protein per kilogram of body weight per day. For strength training specifically, the upper end of that range applies. A meta-analysis of 49 studies involving over 1,800 participants found that the protein intake associated with the greatest muscle gains was 1.6 grams per kilogram per day.
In practical terms, a 180-pound (82 kg) person aiming to maintain muscle should eat roughly 115 to 160 grams of protein daily. Below 1.0 gram per kilogram per day, the risk of muscle loss increases significantly. Above 1.3 grams per kilogram per day, you’re in a range associated with actually gaining muscle mass. So if you’re going to be imprecise about anything, err on the side of more protein rather than less.
How you distribute that protein matters too. Spreading it across meals rather than loading it all into dinner gives your body repeated signals to build and repair muscle throughout the day. Consuming protein around your workout window, whether before, during, or after, supports better recovery and greater gains in lean mass over time.
Older Adults Need More Protein Per Meal
As you age, your muscles become less responsive to the protein you eat. The amino acid leucine, which acts as the primary trigger for muscle building, needs to hit a higher threshold in older adults to kick-start the process. Research estimates that older adults need about 3 to 4 grams of leucine per meal, which translates to roughly 25 to 30 grams of protein per meal. Younger adults can get by with less per sitting.
This doesn’t necessarily mean older adults need more total daily calories, but it does mean the composition of those calories shifts. Choosing protein sources naturally rich in leucine (dairy, eggs, poultry, fish, and beef are all strong options) becomes more important than simply hitting a total protein number. Splitting daily protein into meals of at least 25 to 30 grams each is a practical strategy for maintaining muscle as you age.
Carbs and Fat Fill In the Rest
Once your protein target is set, the remaining calories come from carbohydrates and fat. Neither has a magic ratio for muscle maintenance, but carbohydrates play an important supporting role by replenishing glycogen, the stored energy your muscles use during training. Higher carbohydrate intake leads to greater glycogen replenishment after exercise, which helps you maintain the training intensity needed to keep your muscle.
A reasonable starting point is to fill 40 to 50% of your total calories with carbohydrates and let fat make up the remainder after protein and carbs are accounted for. Fat should stay above about 20% of total calories to support hormone production, including testosterone, which plays a role in muscle maintenance. Beyond those floors, personal preference and training style should guide the split.
Training Is Non-Negotiable
Even with perfect nutrition, you will lose muscle without a training stimulus. The good news: maintaining muscle requires far less effort than building it. Research shows that younger adults can preserve muscle size and strength for up to 32 weeks with just one strength training session per week, performing as few as one set per exercise, as long as the weight stays heavy relative to their capacity. Older adults generally need two sessions per week and two to three sets per exercise to achieve the same effect.
The key variable is intensity, not volume. Dropping from five sets to one set won’t cost you muscle, but dropping from heavy weights to light weights will. If life gets busy and gym time shrinks, prioritize keeping the load challenging over doing more sets or more exercises.
Can You Build Muscle at Maintenance Calories?
Yes, though the results depend on your training experience. People who are new to resistance training, or who carry extra body fat, can gain muscle even in a calorie deficit because their body can redirect stored energy toward building new tissue. At maintenance calories, this effect is even more pronounced. Your body doesn’t strictly require a calorie surplus to add muscle. The energy cost of building new muscle tissue can be covered by internal resources, especially when protein intake is adequate.
For experienced lifters, the window is narrower. Body recomposition (losing fat while gaining muscle at maintenance calories) still happens, but it’s slower and less dramatic. The primary stimulus for muscle growth after physical maturity is mechanical tension from progressive resistance training, not excess calories. Eating above maintenance may speed the process slightly, but it isn’t a prerequisite for muscle gain, and it guarantees additional fat gain alongside any new muscle.