How to Increase Metabolism Naturally (Science-Backed Methods)

Nobody warns you. You’re cruising along in your 30s, eating more or less what you always have, moving more or less the same amount. And then something shifts. The number on the scale climbs a little. Energy dips. Recovery takes longer. Somewhere in the back of your mind, you start questioning whether it’s time to start figuring out how to increase metabolism. Because the things that once worked flawlessly aren’t anymore. 

We’ve all been there. At least most people, if not all. And the frustrating part isn’t that the answers don’t exist. They do, and the science behind them is solid. It’s that the internet is absolutely cluttered with bad advice dressed up as “wellness tips.”  

So, here we cut through all the bad advice you’ve received about how to naturally increase metabolism.  

What Even Is Metabolism? Why Does It Slow Down After A Certain Age? 

To most people, metabolism means how fast they gain or lose weight. Well, that’s just the tip of it. Technically, metabolism is just any type of chemical reaction taking place in your body to keep systems functioning well and sustain life. All these processes need energy. Breathing. Digesting. Growing hair. Fidgeting in your chair. All of it burns energy. 

Your basal metabolic rate (BMR) is the biggest chunk, about 60–75% of your daily calorie burn. That’s what your body uses just existing. Not exercising. Not even moving. Just… being. So, when you hear someone say they’ve got a slow metabolism, they’re just complaining about a low BMR. And yes, it can change as we grow older or undergo hormonal changes. Also, a change in your muscle mass can trigger a change in your BMR. It even affects how the different organs in your body receive oxygen. In fact, the last part is critical. Yet few people talk about.  

Slowing down of metabolism can actually start way earlier than you can expect. Studies have indicated that your muscles, the most metabolically active tissue, start declining at 30 years at a rate of 3 to 8% per decade. As your muscle mass declines, so does your metabolism. Even when you’re at rest doing nothing, the number of calories your body burns reduces.  

Hormonal changes further compound this, especially for women going through perimenopause and menopause. Metabolism doesn’t break; it just gets to a level where it needs more support.  

The Connection Between Oxygen and Metabolism 

Before getting into how to increase metabolism, let’s take an important nerdy detour. Just 60 seconds of high school biology. The mitochondria, the microscopic power plants in every cell, use oxygen to synthesize ATP (adenosine triphosphate). This is the universal currency of energy. That means, without oxygen, no ATP. And a slow ATP production means your metabolic rate also tanks. More like starting a campfire with wet wood. It just doesn’t work.  

Here’s where carbon dioxide (CO2) enters the conversation. CO₂, believe it or not, helps your hemoglobin release oxygen to your tissues. It’s called the Bohr effect. When the CO2 level is not adequate, your body holds onto oxygen instead of releasing it for use where it’s needed. That happens because the brain hasn’t received a trigger that the oxygen level is low. That only happens when CO2 builds up.  

This is the exact knowledge that wellness therapies like carboxytherapy tap into. By increasing microcirculation and tissue perfusion, CO₂ helps your cells actually use the oxygen you’re breathing. And better oxygen delivery means better energy production. Better energy production means a more efficient metabolism. 

How To Increase Metabolism in 10 Natural Ways 

You’ve now seen metabolism and oxygen intake go hand in hand. So, what can you do to increase your hemoglobin’s affinity for oxygen and subsequently enhance metabolism? Here are 10 ways.  

1. Build Muscle Like Your Metabolic Rate Depends on It  

Yes, your metabolic rate depends on it, actually. And strength training is one of the best ways you can leverage towards building more muscle. Sadly, not many people are doing it consistently. At rest, a pound of muscle can burn about 6 calories a day. But fat only burns 2. The gap doesn’t sound enormous until you’re considering adding 10 pounds of lean mass over a year. Suddenly, your resting metabolism is meaningfully higher without any other changes. 

Resistance training burns calories during the workout while also creating what is termed as excess post-exercise oxygen consumption (EPOC). This is the afterburn effect, where your metabolism stays high for hours after you’re done training. A study has shown that EPOC from resistance training can last up to 38 hours after a workout in some people.  

So, if you’re looking for how to increase metabolism after 40, you should start here. And this applies to both men and women. Resistance training two to three times per week. Gradually increase the weight or volume over time. This is non-negotiable if you’re keen on fighting the age-related muscle decline that’s dragging your metabolism down. 

2. Don’t Skip Protein (Seriously) 

Your body needs macronutrients for efficient function. However, protein is the one that does the majority of metabolic heavy lifting. First, it has the highest thermic effect of food (TEF). That’s the energy needed to digest and metabolize food. During digestion, your body burns about 20 to 30% protein calories, 5-10% for carbs, and 0-3% for fat. So, eating a high-protein workout is actually a mini workout.  

Second, adequate protein preserves lean muscle mass, especially critical if you’re in a calorie deficit trying to lose weight. Cut calories without sufficient protein, and your body will happily cannibalize muscle for fuel, tanking your metabolism in the process. This is the part most crash diets completely ignore. 

Aim for roughly 0.7–1 gram of protein per pound of body weight. That’s higher than most general guidelines suggest, but it’s where the research on muscle preservation lands. Eggs, Greek yogurt, chicken, lentils, cottage cheese — boring list, yes, but it works. 

3. Protein Timing Actually Matters 

We’ve talked about ensuring your diet has sufficient proteins if you’re to keep your metabolism high. But timing your protein is just as important. You should spread your protein evenly across different meals. Not loading up just at dinner or lunch. Doing this boosts synthesis more effectively.  

What does spreading your protein through meals mean? Eggs at breakfast. Chicken or tofu at lunch. Beans or fish at dinner. And add a snack like Greek yogurt somewhere in between.  

4. Sleep: The Underrated Metabolic Variable 

When most people are looking for how to increase metabolism, sleep rarely comes to mind. Even if it does, it doesn’t get enough airtime. Sleep is when your body does its most intensive repair work. Secreting growth hormone, regulating hunger hormones like ghrelin and leptin, and consolidating muscle protein synthesis from the day’s training. Cut sleep short and all of that gets disrupted.  

Research found that people deprived of sleep lost significantly more lean mass and less fat when under a calorie-deficient diet. Lack of adequate sleep also causes higher cortisol levels, which promote the storage of fat and breakdown of muscle. These are two things you don’t want to deal with when trying to raise your metabolism.  

Target at least 7 hours of sleep. Not five or six. And no, “I’ll catch up on Saturday” doesn’t cut it either. To get good results, you need consistent, quality sleep.  

5. Carbon Dioxide Therapy – Unconventional But Works 

Remember that detour about oxygen delivery? Let’s circle back. CO2 is more than just a waste of the respiratory process; it’s a signaling molecule that tells your blood to let go of oxygen for the tissues to use. With therapies like the CO2 inhaler and BodyStream CO2, tissue perfusion and microcirculation can receive a boost. That’s just another way of saying delivering oxygen into the cells for energy production.  

You’re probably wondering, how is this even related to metabolism. As we mentioned earlier, the mitochondria in your cells use oxygen to produce ATP. When oxygen is limited, production of ATP also becomes limited. So, these CO2 therapies indirectly contribute to improved metabolism by reducing the bottlenecks to oxygen delivery.  

This is also backed by clinical research. In a 2022 pilot study on carboxytherapy (medical CO2 therapy), it was found that these therapies improve tissue metabolism and local circulation in healthy women.  

The Specific Challenge of Metabolism After 40 for Women 

Here’s the thing you probably haven’t been briefed about if you’re getting into your 40s. How to increase metabolism after 40 female isn’t the same as any other approach anyone would adhere to when trying to enhance their basal metabolic rate. When you get into perimenopause, which can happen as early as your thirties, hormones start playing weird, unpredictable games. Estrogen and progesterone start to fluctuate and then eventually start falling off a cliff.  

What does that actually do to your body? A few annoying things. Fat distribution isn’t the same anymore. It starts to settle around the middle section. This is the visceral fat, termed the dangerous fat. They start settling less under your skin, where they used to hang out a lot. Insulin resistance also chips in, and suddenly you can’t handle carbs like you used to.  

Muscle loss also accelerates, even if you’re still doing the same workouts as you used to in your 30s. So, when you hit 40, your metabolism isn’t playing by the same rules as for everyone else.  

What Works To Keep Metabolism High After 40  

Strength training is non-negotiable here. More importantly, when in your mid-40s. Not that you need to deadlift like a professional, but you have to challenge your muscles consistently. Or you’ll lose them, and that means more trouble for your metabolism.  

Next, cortisol management. This one sounds like wellness influencer fluff, but honestly, it’s more important than you can imagine. Sleep deprivation and chronic stress will cause your metabolism rate to tank as the body enters conservation mode. So, just go to bed, get enough sleep, and maybe let loose a little.  

Carb timing is equally important. A small hack worth paying attention to: you should eat most of your carbs around the time of your workout. This is when your insulin sensitivity is at its peak. Instead of storing those carbs as fat, your body will redirect them towards muscle repair.  

Final Thoughts

When looking for how to increase metabolism, the strategies you find aren’t going to restore your metabolism to that of an 18-year-old. It’s not realistic. The methods we’ve discussed here, and probably you’ve seen elsewhere, are going to get rid of obstacles your body faces so metabolism can happen at the rate it should.  

So, focus on strength training. Include protein in all your meals. Get quality sleep, and don’t overlook simple, yet effective stuff like CO2 therapy that actually works. 

How to increase metabolism after 40 isn’t a mystery; it’s a checklist, and you probably are already aware of most of the items, like we’ve mentioned.  Actually, the tough part isn’t knowing, it’s doing. So, just pick one from this list. Just one. Start tomorrow, and see how things change.