Slowing down your metabolism is possible, but it works differently than most people expect. You can’t flip a switch, and the changes tend to be modest. Your body burns most of its calories just keeping organs running, so the adjustable portion of your daily energy expenditure is smaller than you might think. Still, there are real, evidence-based ways to shift the balance: eating differently, moving less intensely, sleeping more, and in some cases, working with a doctor to rule out a medical cause like hyperthyroidism.
Why Your Body Burns What It Burns
Your basal metabolic rate, the energy your body uses at rest, accounts for the largest share of your daily calorie burn. Most of that energy goes to your brain, liver, kidneys, and heart. Muscle tissue contributes only about 20% of resting energy expenditure. One pound of muscle burns roughly 5 to 7 calories per day at rest, which means even someone with significantly more muscle mass than average isn’t burning dramatically more at baseline.
On top of your resting metabolism, your body spends energy digesting food (called the thermic effect of food) and on all the movement you do throughout the day, from fidgeting to walking to the store. That daily movement, separate from formal exercise, can vary by up to 2,000 calories per day between two people of similar size. This is often the biggest variable and the easiest place to make changes.
Eat More Fats and Simple Carbs
Your body burns calories just processing food, and the amount depends heavily on what you eat. Protein costs the most energy to digest, raising your metabolic rate by 15 to 30% of the calories consumed. Carbohydrates require 5 to 10%, and fats require the least at 0 to 3%. If you’re trying to slow your metabolism, shifting your diet away from high-protein meals and toward meals richer in healthy fats (avocado, olive oil, nuts, full-fat dairy) will reduce the energy your body spends on digestion.
This doesn’t mean abandoning protein entirely. You still need it for basic body functions. But if you’re currently eating a very high-protein diet, bringing it down to a moderate level and replacing those calories with fats will lower your overall metabolic output from digestion alone.
Eat Enough Calories (and Then Some)
One of the strongest metabolic responses your body has is slowing down when you eat less. Research published in Metabolism found that adaptive thermogenesis kicks in within the first week of calorie restriction, reducing daily energy expenditure by an average of 178 calories per day. That slowdown remains remarkably stable for weeks. This is your body protecting itself from starvation.
The flip side is relevant here: if you’re eating enough calories or slightly above your needs, your body won’t trigger that conservation mode. It will burn at its normal rate. If your goal is to gain weight while slowing metabolism, consistently eating above your calorie needs, especially from fat-rich foods, gives your body more raw material to store without ramping up the calorie-burning machinery the way protein-heavy or complex-carb-heavy meals would.
Reduce Movement Throughout the Day
Formal exercise is the obvious target, but the calories burned from everyday movement often matter more. Walking, standing, fidgeting, carrying groceries, cleaning your house: all of it adds up. If you’re someone who paces while on the phone or takes the stairs everywhere, those habits are quietly burning hundreds of extra calories daily.
To meaningfully lower your total energy expenditure, consider sitting more during work, driving instead of walking for short trips, and choosing less physically demanding leisure activities. If you currently do intense cardio or endurance training, scaling back to lighter, shorter workouts will have a noticeable effect. Strength training, while it doesn’t burn enormous calories in the moment, does maintain and build muscle tissue that burns slightly more at rest, so reducing heavy lifting sessions can contribute to a small decrease in resting metabolism over time.
Prioritize Sleep
This one sounds counterintuitive. Sleep deprivation actually disrupts metabolism in ways that seem like they’d help with weight gain (increased hunger, more fat storage), but the overall effect is harmful, not helpful. Poor sleep raises ghrelin (the hormone that drives hunger) and lowers leptin (the hormone that signals fullness), leaving you constantly hungry. It also disrupts cortisol patterns, pushing levels higher during the day, which promotes belly fat accumulation and insulin resistance.
Getting consistent, adequate sleep (typically 7 to 9 hours) actually supports a more stable, predictable metabolic rate. If your fast metabolism is driven partly by stress, poor sleep, or hormonal chaos, fixing your sleep could paradoxically help your body settle into a calmer metabolic state. Your body does its most efficient repair and storage work during deep sleep, so skimping on it doesn’t slow metabolism in a useful way. It just makes your body worse at using the calories you give it.
Rule Out Hyperthyroidism
If your metabolism feels unusually fast, with unintended weight loss, constant hunger despite eating well, a racing heart, anxiety, or heat intolerance, the cause may be medical. Hyperthyroidism pushes your body into a hypermetabolic state, increasing resting energy expenditure and ramping up how quickly you burn through carbohydrates, fats, and amino acids. Thyroid hormones control energy storage and expenditure throughout the body, so when they’re overproduced, everything speeds up.
A simple blood test can check your thyroid hormone levels. If hyperthyroidism is the cause, treatment can bring your metabolism back to a normal range, which would be far more effective than any lifestyle change alone.
What About Aging?
One thing working in your favor if you’re patient: metabolism does slow naturally with age, though not as early as most people believe. Research from a large international study found that metabolic rate stays remarkably stable from about age 20 through 60. After 60, it declines by roughly 0.7% per year. By age 90, total energy expenditure is about 26% lower than in middle-aged adults. So while aging will eventually slow things down, it’s not a practical strategy for someone in their 20s, 30s, or 40s hoping for near-term changes.
Understand the Risks of Going Too Far
There’s a meaningful difference between wanting a slightly slower metabolism to support weight gain and actually suppressing your metabolic rate to unhealthy levels. A chronically low metabolic rate is associated with insulin resistance, where your cells stop responding properly to insulin and blood sugar rises even as your body produces more of it. Over time, this can progress to type 2 diabetes.
The cluster of problems that often travels with metabolic dysfunction includes high blood pressure, elevated cholesterol, excess abdominal fat, and increased risk of heart attack and stroke. Conditions like fatty liver disease, polycystic ovary syndrome, and sleep apnea are also linked to metabolic disruption. The goal should be to bring your metabolism to a healthy, comfortable baseline rather than to suppress it as far as possible. If you’re struggling to gain weight despite eating well, a doctor or registered dietitian can help identify whether the issue is truly metabolic rate or something else, like poor calorie absorption or an underlying condition.