Does Metabolism Slow Down After 50? What Science Shows

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Does metabolism slow down after 50? Mostly not in your 50s. A large 2021 study of daily energy use found that, once body size and body composition are accounted for, the number of calories adults burn stays flat from about age 20 to about age 60 and then falls by roughly 0.7 percent a year. Muscle mass and daily activity are the parts you can influence.

This page covers what that study measured, how resting energy changes with age, why weight still creeps up, and what to do about it. It sits inside the weight loss for men over 50 guide. For the diet side, see calorie deficit for men over 50.

Table of Contents

What Did the Large Study of Metabolism and Age Find?

It found that adult energy expenditure does not slow until about age 60. In 2021, Herman Pontzer and colleagues published a pooled database in the journal Science. It covered 6,421 people from 29 countries, aged 8 days to 95 years, and measured their daily energy expenditure with doubly labeled water, a method that tracks calories burned in normal life. About 64 percent of the people were female.

The team adjusted each person’s calorie burn for fat-free mass and fat mass. After that adjustment, they described four life stages. Energy use per unit of body size peaks around age 1, declines to adult levels near age 20, stays stable from 20 to 60, then declines in older adults.

When Does Metabolism Start to Slow Down?

Their statistical break point for total energy expenditure was 63.0 years, with a 95 percent confidence interval of 60.1 to 65.9. After that point, adjusted expenditure fell by 0.7 percent a year. People in their nineties burned about 26 percent less than middle-aged adults of the same size and composition. In adults, sex had no detectable effect on adjusted expenditure.

What the Study Does Not Tell Men Over 50

It was not a study of men over 50, and most participants were women. The estimate for basal (resting) expenditure put the break point earlier, at 46.5 years, but the confidence interval was wide (40.6 to 52.4) because few resting measurements existed for ages 45 to 65. The authors also note that the decline after 60 tracks with falling fat-free mass and activity level, and may also reflect age-related changes in organ metabolism. This is a pooled comparison of different people, not a follow-up of one group of men for decades.

How Many Calories Does a Man Burn at Rest at 50?

The Mifflin-St Jeor equation estimates a man’s resting energy expenditure as 10 times weight in kilograms, plus 6.25 times height in centimeters, minus 5 times age in years, plus 5. Researchers built it from 498 healthy adults aged 19 to 78 (average age 45), measuring resting energy with indirect calorimetry.

The age term is small. Each added year subtracts 5 calories a day when weight and height stay the same. Worked through the equation, a 5-foot-11, 198-pound (180 centimeters, 90 kilograms) man comes out at about 1,780 calories a day at rest at age 50 and about 1,730 at age 60. Treat it as an estimate, not a measurement of your own body.

Why Do Men Still Gain Weight in Their 50s?

Two possible contributors are less muscle and less movement. The studies below speak to each piece, but none of them follows men through their 50s, so read this as a reasoned explanation, not a proven chain of cause.

Does Losing Muscle Mass Slow Metabolism?

A little. A 2012 quantitative review by Mitchell and colleagues put the median rate of muscle loss at 0.47 percent a year in men, based on studies comparing adults aged 18 to 45 with adults over 65. Longitudinal studies of men around 75 showed losses of 0.80 to 0.98 percent a year, and strength fell faster, at 3 to 4 percent a year.

Muscle’s resting calorie burn is modest. A 2010 study of 131 non-obese adults estimated about 12.6 calories per kilogram per day for skeletal muscle and 4.4 for fat tissue in adults over 50. Swapping 5 kilograms of muscle for fat would lower resting burn by roughly 40 calories a day, using those two figures. The bigger reason to protect muscle is strength, since the Mitchell review reports that loss of strength is a more consistent risk for disability and death than loss of muscle mass.

Does Daily Movement Matter More Than You Think?

Possibly, though the evidence is indirect. Non-exercise activity thermogenesis, the energy you spend walking, standing and fidgeting, varied enough in one overfeeding study of 16 non-obese volunteers to account for a 10-fold difference in how much fat each person stored. Those volunteers were not older men, so the size of the effect may differ for you. My read: if a desk job has cut your daily steps, that is the easiest piece to win back.

How Can You Keep Your Metabolism From Slowing After 50?

You cannot change the age curve, but you can protect the muscle and activity that sit under it. Three habits have official guidance behind them: strength training, enough protein and enough sleep.

Lift Weights at Least Two Days a Week

The CDC recommends adults get 150 minutes of moderate-intensity activity a week plus at least 2 days of muscle-strengthening activity. My suggestion: treat the two strength days as the part you do not skip, because holding muscle and strength is what the Mitchell review warns about losing.

If you train at home, a set of bands is a simple way to cover those days. One option is the WHATAFIT resistance bands with handles, 150 lb exercise bands set, which the listing describes as having five stackable levels, a door anchor, ankle straps and a carry bag. Dumbbells or a gym membership are other ways to cover those days. As an Amazon Associate we earn from qualifying purchases.

Eat Enough Protein

The 2025 to 2030 Dietary Guidelines for Americans set a protein goal of 1.2 to 1.6 grams per kilogram of body weight per day, adjusted for your calorie needs. At 200 pounds (about 91 kilograms) that is roughly 109 to 146 grams a day. The maintain muscle mass after 50 page covers training and food in more detail.

Sleep at Least Seven Hours

The CDC lists 7 or more hours of sleep for ages 18 to 60 and 7 to 9 hours for ages 61 to 64. In a small 2010 trial, 10 overweight adults with an average age of 41 ate a reduced-calorie diet for 14 days with either 8.5 or 5.5 hours of sleep opportunity a night. The short-sleep period cut the share of weight lost as fat by 55 percent and raised the loss of fat-free mass by 60 percent. The trial was short and tiny, but it fits the advice to protect your sleep while you diet. If the scale still will not move, why you can’t lose weight as a man over 50 walks through the other common causes.

When Should You See a Doctor About a Slow Metabolism?

My suggestion: see your doctor if your weight changes without a clear reason, or if you feel unusually tired, cold or sluggish. Those are worth a check-up on their own, and a doctor can order the blood tests that a general article cannot replace. Do not start supplements or hormone treatments on the strength of a “slow metabolism” label alone.

Frequently Asked Questions

At What Age Does Metabolism Start to Slow Down?

In the 2021 Science analysis of 6,421 people, size-adjusted energy expenditure began to decline at about age 63, with a confidence interval of 60 to 66. Before that, from about 20 to 60, it was stable.

Does Metabolism Slow Down Faster in Men or Women?

In adults, that analysis found no detectable effect of sex on size-adjusted energy expenditure. It was not designed to compare men and women over 50 directly, so it cannot settle the question for that age group.

Is It Harder to Lose Weight After 50?

It can be, but the study found no drop in size-adjusted energy expenditure in the 50s, so a slower metabolism is a less likely explanation. Muscle, activity, sleep and eating habits are the levers you can work on.

Can You Speed Up Your Metabolism After 50?

You cannot change the age curve itself. What you can do is hold on to muscle with strength training, eat enough protein, stay active through the day and sleep enough. The study does not show that any of these reverses the decline after 60, but they protect the muscle and activity that the decline is tied to.

How Many Calories Does a 50-Year-Old Man Burn a Day?

It depends on size and activity. The Mifflin-St Jeor equation puts resting burn near 1,780 calories for a 5-foot-11, 198-pound man at age 50, before any movement or exercise is added. Total daily burn is higher.

This page is general information, not medical advice. Talk with your doctor before changing your diet, starting an exercise program or taking supplements, especially if you have diabetes, heart disease, kidney disease or high blood pressure, or take medication.

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Does Metabolism Slow Down After 50? What the Research Shows