Gymondo Magazin

How Your Metabolism Changes in Your 20s, 30s and 40s

Remember the moment it hit you? You’d been eating the same amount of calories and exercising regularly but you noticed an upward incline on the scale. Or, maybe you came home from a night out drinking and could barely get out of bed the next day.

Those days of bouncing back quickly after a night on the town are long gone. If you have no clue what’s going on, there are clear signs pointing to a slowed metabolism. 

While it differs from person to person, your metabolism slows as you age. For some, the decline starts in the 20s or 30s and for the lucky ones, it may not happen until the age of 40 or even 50.

No matter when it starts, it’s important to understand how your metabolic system functions so you can keep your engine running at full speed. 

Related: Over 50? Here’s Everything You Need to Know About Working Out as You Age

The Roaring 20s

Oh, the good ole days—the days when you could eat all the fried food you wanted and never gain a pound. Like most people, in your 20s, you probably experienced your highest resting metabolic rate (RMR).

A high RMR means your body burns the most amount of calories in a resting state—sleeping, watching TV, sitting at your desk. While your RMR is somewhat based on genetics, it’s largely determined by how active you are. 

While inactivity may not seem to be a problem in your early 20s, it can slowly catch up to you as you age. 

Your body continues to build bone until you reach the age of 25, which boosts your calorie burn. However, in your late 20s, you may start to notice a decline. You can’t eat as frivolously as you did in your early 20s and your body can’t bounce back as quickly. 

The good news is that your body can recover more quickly with a cleaner diet and regular exercise.  

Add Gymondo’s Pure Cardio program to burn fat and boost your metabolism. 

30 Something 

Guess what? Your RMR is directly related to your muscle mass. The more muscle you have, the more calories you’ll burn, even when you’re not working out. So, if you haven’t started strength training by your 30th birthday, it’s time to begin! 

Try Gymondo’s Triple Strength program to boost your metabolism, build lean muscle and burn calories. 

By the time you hit your 30s, your muscle mass starts to slowly decline. In fact, you lose about one percent each year. But you can easily reverse this natural aging process. 

When you don’t use your muscles, you start to store more fat. To prevent this from occurring, add strength training to your workout routine at least three times per week. 

And as a woman, it’s even more important to strength train regularly. Because men have more testosterone, which contributes to a lower body fat percentage, and more muscle mass, it’s easier for them to keep their metabolism running at full throttle. 

To add insult to the injury, your 30s are marked by a decline in human growth hormone (HGH), leading to lowered metabolism.

Lifting weights produces HGH, which keeps your metabolism running as fast as (or faster than) it did when you were 20. So, grab your dumbbells and get started! 

This Is 40? 

By the time you’ve hit 40, you’ve either contemplated dieting or have tried it already.

Research suggests the average woman has dieted for more than six years by the time she reaches 40.

Yet, 95 percent of dieters regain the lost weight (and more) within five years, a term coined yo-yo dieting. 

But it’s important to keep your metabolism from rollercoastering. As your levels of estrogen, progesterone and HGH decrease, your metabolism follows suit. This is where the power of protein comes in handy.

Protein helps keep you full for longer and feeds your muscle tissue, repairing any tears caused by working out. With ample sources of protein, your muscles start to repair and grow stronger. 

While the amount of protein varies by person, it’s suggested to eat a lean source of protein with each meal to keep your metabolism running strong all day long. This equates to 100-200 grams per day. 

Lean Sources of Protein


Edamame beans
Organic eggs
Unsweetened soy milk
Beans and legumes

And here’s some good news: a sedentary woman in her 20s and 30s can actually have a higher metabolic rate in her 40s if she exercises and eats clean. 

Find out why fad diets don’t work

The Bottom Line

Eat a well-balanced diet consisting of lean sources of protein and complex carbohydrates (sweet potatoes, brown rice, bulgar, fruits, vegetables), limit your intake of sugary and fried foods and get plenty of exercise. This is the triple threat you need for a speedy metabolism no matter what your age.  

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Kristy Crowley

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Note: People who have diabetes or are pregnant are not advised to participate in the online program without consulting their doctor first. The online program is also not suitable for treating pathological overweight.