Slowing your metabolism comes down to changing how much energy your body burns at rest and during daily activity. Most people searching for this are trying to gain weight, struggling with an overactive thyroid, or burning through calories faster than they can eat them. The practical levers you can pull involve what you eat, how you move, how much you sleep, and the temperature you live in.
What Actually Drives Your Metabolic Rate
Your resting metabolic rate, the calories you burn just staying alive, is primarily determined by how much lean tissue you carry. Fat-free mass (muscle, organs, bone) accounts for about 63% of the variation in metabolic rate between people. Body fat contributes another 6%, and age adds about 2%. Sex, surprisingly, doesn’t independently affect metabolic rate once body composition is accounted for. Thyroid hormone levels also play a role, particularly in men, where the hormone T4 explained 25% of the remaining metabolic variation in one study.
About a quarter of the variation in resting metabolism between individuals remains unexplained by any measurable factor. This is the genetic and biological “luck of the draw” portion you can’t directly control. But the factors you can influence, especially body composition, activity level, and diet, give you real room to shift your daily calorie burn downward.
Reduce Movement Outside of Exercise
One of the largest and most overlooked components of daily calorie burn is non-exercise activity thermogenesis, or NEAT. This includes every movement that isn’t structured exercise: fidgeting, standing, walking to the kitchen, pacing while on the phone. Research from the Mayo Clinic found that NEAT can differ by up to 2,000 calories per day between two people of similar size. In one study, obese individuals sat an average of two and a half hours more per day than lean individuals, while lean people stood or walked more than two hours longer.
If you want to lower your total energy expenditure, reducing incidental movement is one of the most effective strategies. That means sitting more, taking fewer steps throughout the day, driving instead of walking, and generally minimizing restless movement. This won’t feel like a “health hack,” and for most people it isn’t advice you’d want to follow long-term. But if your goal is specifically to slow your metabolism and conserve energy, cutting NEAT is powerful precisely because it operates all day long.
Choose Foods With a Lower Thermic Effect
Your body burns calories just digesting food, a process called the thermic effect of food. Different macronutrients cost very different amounts of energy to process. Protein is the most metabolically expensive: your body uses 20 to 30% of protein calories just to digest and absorb it. Carbohydrates cost 5 to 10%, and fats cost only 0 to 3%.
To reduce the energy your body spends on digestion, shift your diet toward a higher proportion of fats and carbohydrates and a lower proportion of protein. This doesn’t mean eliminating protein, which your body still needs for basic functions. It means that if you’re currently eating a high-protein diet, replacing some of those calories with fats like oils, butter, nuts, and avocados will reduce your total metabolic burn. Fats are also the most calorie-dense macronutrient at 9 calories per gram, making it easier to eat in a surplus without feeling overly full.
Eat More Calories Than You Burn
Consistently eating above your maintenance calories signals your body to store energy rather than ramp up expenditure. Studies on caloric surplus in active adults have used overfeeding ranges from about 370 to 800 extra calories per day, with some going as high as 1,250 extra calories. A moderate surplus of 300 to 500 calories per day is a practical starting point for gradual weight gain without digestive discomfort.
To estimate your baseline calorie needs, the Mifflin-St Jeor equation is considered the most accurate formula available. A systematic review found it predicted resting metabolic rate within 10% of measured values in more people than any competing equation, for both normal-weight and obese individuals. You can find calculators online that use this formula. Once you know your estimated maintenance calories, add your surplus on top.
Meal Frequency Doesn’t Matter Much
You may have heard that eating fewer, larger meals slows your metabolism compared to eating many small meals throughout the day. The evidence doesn’t support this in any meaningful way. Studies comparing two meals versus six meals per day at the same total calorie intake found no significant difference in daytime energy expenditure. A meta-analysis of meal frequency research found negligible differences in body weight and composition changes between high and low meal frequencies.
What matters is total calorie intake, not how you divide it up. Eat in whatever pattern helps you consistently hit your calorie target. For some people, that’s three large meals. For others, it’s frequent snacking. Neither approach will independently speed up or slow down your metabolism.
Sleep More, Not Less
Sleep deprivation might seem like it would slow things down, but it actually disrupts your appetite-regulating hormones in ways that make weight management harder, not easier. People who sleep only 5 hours compared to 8 hours have about 15.5% lower levels of leptin (the hormone that signals fullness) and 14.9% higher levels of ghrelin (the hormone that signals hunger). Short sleep is associated with higher BMI, but through a chaotic, unhealthy pathway involving increased appetite, impaired blood sugar regulation, and fat storage in the wrong places.
Getting a full 7 to 9 hours of sleep supports the kind of metabolic slowdown you actually want. Adequate sleep allows your body to spend more time in a low-energy resting state, recover properly, and regulate hormones that govern how efficiently you store and use energy. It also reduces the restless, anxious energy that drives up NEAT.
Stay Warm
Your body burns extra calories maintaining its core temperature when the environment is cold. The thermoneutral zone for a clothed human is roughly 72 to 77°F (22 to 25°C). Below that range, your body activates heat-producing mechanisms that increase metabolic rate. Research in animals shows that energy expenditure at thermoneutrality is about 45% lower than in a cool environment, because the body doesn’t need to allocate extra energy for heat production.
The human effect is less dramatic than in small animals (we have a much lower surface-area-to-volume ratio), but the principle holds. Keeping your living and working environment warm, dressing in layers, and avoiding prolonged cold exposure will reduce the metabolic cost of temperature regulation. If you tend to keep your house cool or take cold showers, warming things up is one of the simplest changes you can make.
Cut Back on Intense Exercise
Vigorous exercise, particularly high-intensity interval training and heavy resistance training, elevates your metabolic rate for hours after you finish. This afterburn effect means your body continues spending extra energy on recovery well beyond the workout itself. Resistance training also builds muscle over time, and since lean mass is the single largest driver of resting metabolism, adding muscle will push your metabolic rate higher.
If your goal is to slow metabolism, reduce exercise intensity and volume. Light walking is fine and burns relatively few calories. But structured cardio sessions, weight training, and high-intensity work all increase both your immediate calorie burn and your resting metabolic rate over time. Scaling these back, or eliminating them temporarily, will lower your total daily energy expenditure.
Rule Out Hyperthyroidism
If your metabolism feels uncontrollably fast, with symptoms like unintentional weight loss, rapid heart rate, tremors, heat intolerance, anxiety, excessive sweating, or increased frequency of bowel movements, you may be dealing with an overactive thyroid rather than simply a “fast metabolism.” Hyperthyroidism affects thyroid hormone levels in a way that forces your body to burn energy at an accelerated rate regardless of what you eat or how you live.
Diagnosis involves a simple blood test measuring TSH, free T4, and total T3. People with overt hyperthyroidism have suppressed TSH with elevated T4 and T3. One important note: high-dose biotin supplements (common in hair and nail products) can falsely skew these test results, so mention any supplements to your provider before testing. If hyperthyroidism is confirmed, treating the underlying thyroid condition is far more effective than any lifestyle change at bringing your metabolic rate back to a normal range.