How To Improve Metabolism And Digestion? Facts vs. Myths
The most effective ways to improve your metabolism are building muscle with strength training, staying active throughout the day, eating enough protein, sleeping well, and avoiding crash diets.
For digestion, the biggest lever is simple: eat more fiber and drink enough water. Most people fall far short.
Only about 5% of American adults meet the daily fiber recommendation. Metabolism is also less fragile than many believe.
A landmark 2021 study in Science of more than 6,400 people found that metabolism stays essentially stable from age 20 to 60 and only declines by about 0.7% a year after that.
This article explains what metabolism and BMR really are, which strategies boost metabolism in a meaningful way, why “metabolism booster” products disappoint, how to support digestion, and what to do if you’re trying to gain weight instead.
What Is Metabolism?
Metabolism is all the chemical processes your body uses to turn food into energy and keep you alive, from breathing and circulating blood to repairing cells and digesting meals.
When people talk about a “fast” or “slow” metabolism, they usually mean how many calories the body burns each day.
What Are The Parts Of Your Daily Metabolism?
Your total daily calorie burn has three main parts:
| Component | What It Is | Share Of Daily Calories |
|---|---|---|
| Resting metabolic rate (RMR) or BMR | Energy to keep your body alive at rest | About 70% to 80% |
| Thermic effect of food (TEF) | Energy to digest and process food | About 10% |
| Physical activity | Exercise and everyday movement | About 0% to 20% (more if very active) |
What Is BMR (Basal Metabolic Rate)?
What is basal metabolic rate? BMR is the number of calories your body burns at complete rest just to keep vital functions running, like your heart, lungs, brain, and organs.
It’s the largest part of your daily calorie burn.
What Affects Your BMR?
| Factor | Effect |
|---|---|
| Body size | Larger bodies burn more calories |
| Muscle mass | Muscle is more metabolically active than fat |
| Age | Stable from 20 to 60; declines slowly after 60 |
| Sex | Men often have higher BMR, mostly due to more muscle |
| Genetics | Some natural variation between people |
| Thyroid hormones | Overactive or underactive thyroid changes metabolism |
| Severe dieting | Can lower metabolic rate |
Does Metabolism Really Slow Down With Age?
Not as much as most people think. Researchers led by Herman Pontzer studied data from more than 6,400 people aged 8 days to 95 years across 29 countries.
After adjusting for body size, they found metabolism:
| Life Stage | What Happens To Metabolism |
|---|---|
| Birth to age 1 | Rises sharply; babies burn about 50% more than adults (adjusted for size) |
| Age 1 to 20 | Slows by about 3% per year |
| Age 20 to 60 | Stays stable |
| After age 60 | Declines about 0.7% per year |
Pontzer said his team saw no evidence of metabolism “falling apart” at 30. The study also found no metabolic slowdown during menopause.
So if you’re gaining weight in midlife, changes in activity, muscle, sleep, and eating habits are more likely culprits than a “broken” metabolism.
How To Increase Your Metabolism Naturally?
Here’s how to increase metabolism naturally with strategies backed by evidence:
| Strategy | Effect On Metabolism | Strength Of Evidence |
|---|---|---|
| Strength training | Builds muscle, raises resting metabolism modestly | Good |
| Eating enough protein | Highest thermic effect of food | Good |
| Moving more throughout the day | Increases daily calorie burn | Good |
| Aerobic exercise | Burns calories, supports heart health | Good |
| Getting enough sleep | Supports healthy metabolic hormones | Supportive |
| Avoiding crash diets | Prevents metabolic slowdown | Good |
| “Metabolism booster” pills | Small, temporary, or unproven effects | Weak |
1. Build Muscle With Strength Training
Muscle burns more calories than fat, even at rest. In one study, 9 months of whole-body resistance training increased resting metabolic rate by about 5% on average, though results varied a lot between people.
Strength training also boosts the calories you burn digesting food. A small study found that after a single resistance training session, the thermic effect of a carbohydrate meal was 73% greater than without exercise.
How to start:
- Train major muscle groups two to three times a week
- Use bodyweight exercises, resistance bands, or weights
- Gradually increase resistance over time
- Include squats, lunges, push-ups, rows, and planks
2. Eat Enough Protein
Your body burns calories digesting food, and protein takes the most energy to process.
On average, the thermic effect of food is about 10% of total energy use, but it differs by nutrient:
| Nutrient | Calories Used To Digest It |
|---|---|
| Protein | 20% to 30% |
| Carbohydrates | 5% to 10% |
| Fat | 0% to 3% |
Foods that boost metabolism are mostly high-protein and minimally processed:
| Food | Why It Helps |
|---|---|
| Eggs | High-quality protein |
| Fish, chicken, lean meats | High protein |
| Lentils, beans, chickpeas | Protein and fiber |
| Greek yogurt, paneer, cottage cheese | Protein-rich dairy |
| Tofu and tempeh | Plant protein |
| Whole grains | Minimally refined grains raise TEF compared with refined grains |
| Vegetables | Fiber and nutrients with few calories |
3. Move More Throughout The Day
Everyday movement, like walking, standing, climbing stairs, and doing chores, adds up. Breaking up long sitting periods also supports circulation and blood sugar.
Simple ways to move more:
- Walk after meals
- Take stairs instead of elevators
- Stand or walk during phone calls
- Set a timer to move every 30 to 60 minutes
- Aim for more daily steps over time
4. Don’t Crash Diet
Severe calorie restriction can backfire. A 2016 study followed 14 contestants from The Biggest Loser six years after the show.
Their resting metabolic rate was about 704 calories per day below their starting level, and their metabolic adaptation was about 499 calories per day below what would be expected for their body size.
In simple terms, their bodies burned about 500 fewer calories a day than expected, even after years, making weight maintenance much harder. Most also regained substantial weight, an average of 41 kg.
Lesson: slow, steady changes, enough protein, and strength training help protect your metabolism better than extreme diets.
5. Sleep Well
Poor sleep can affect appetite hormones, energy, blood sugar, and motivation to exercise. Aim for 7 to 9 hours of good-quality sleep most nights.
How To Speed Up Metabolism? Quick Tips
| Tip | Why It Helps |
|---|---|
| Do strength training 2 to 3 times a week | Builds calorie-burning muscle |
| Include protein at every meal | Highest thermic effect |
| Walk after meals | Burns calories, aids digestion |
| Break up sitting time | Increases daily movement |
| Drink enough water | Supports overall body function |
| Sleep 7 to 9 hours | Supports metabolic health |
| Avoid extreme calorie cuts | Prevents metabolic slowdown |
Do Metabolism Booster Supplements Work?
Most metabolism booster products promise far more than they deliver. Ingredients like caffeine, green tea extract, and capsaicin may cause small, temporary increases in calorie burn, but they don’t replace exercise or healthy eating, and some can cause jitters, rapid heartbeat, or digestive upset.
| Claim | Reality |
|---|---|
| “Melt fat while you sleep” | Not supported |
| “Boost metabolism 300%” | Unrealistic |
| “Fix a slow metabolism in days” | Not supported |
| “Detox teas speed metabolism” | Often contain laxatives, not metabolism boosters |
| “Natural fat burners” | Small effects at best |
Be especially cautious with products containing stimulants or laxatives, like those flagged in our review of Finessa, and talk to your doctor if you have heart problems, high blood pressure, or take medications.
How To Lose Body Fat Without Wrecking Your Metabolism?
How to lose body fat effectively comes down to a modest calorie deficit while protecting muscle:
| Step | Why |
|---|---|
| Aim for slow, steady weight loss | Reduces metabolic slowdown |
| Keep protein intake high | Preserves muscle |
| Strength train regularly | Maintains or builds muscle |
| Stay active daily | Increases calorie burn |
| Prioritize sleep | Supports appetite control |
| Avoid extreme diets | Prevents large metabolic adaptation |
For a complete plan, see how to boost your metabolism for weight loss.
What Is A Fast Metabolism?
What is fast metabolism? It usually means burning more calories than average for your size. Some people naturally burn more due to genetics, more muscle, or higher daily activity.
How To Have A Fast Metabolism?
While you can’t completely change your genetics, you can raise your daily calorie burn by:
- Building more muscle
- Staying active throughout the day
- Eating enough protein
- Avoiding long periods of sitting
- Sleeping well
Signs Of A Slow Metabolism: Should You Worry?
A slow metabolism is often blamed for weight gain, but true metabolic problems are less common than people think.
Possible medical causes include:
| Condition | Possible Signs |
|---|---|
| Hypothyroidism (underactive thyroid) | Fatigue, weight gain, feeling cold, constipation, dry skin |
| Hyperthyroidism (overactive thyroid) | Weight loss, rapid heartbeat, anxiety, heat intolerance |
| Certain medications | Weight changes after starting a new drug |
If you have these symptoms, ask your doctor about a blood test.
How To Slow Down Metabolism For Skinny Guys?
People searching how to slow down metabolism for skinny guys usually want to gain weight or muscle.
You can’t safely “slow down” or “get rid of” your metabolism, and trying to do so through unhealthy habits isn’t a good idea. Instead, focus on eating more and building muscle:
| Strategy | Why It Helps |
|---|---|
| Eat more calories than you burn | Necessary for weight gain |
| Choose calorie-dense healthy foods | Nuts, nut butters, olive oil, dried fruit, whole milk, eggs |
| Eat more often | Several meals and snacks daily |
| Prioritize protein | Supports muscle growth |
| Strength train progressively | Turns extra calories into muscle |
| Drink smoothies or shakes | Easy way to add calories |
| Get enough sleep | Supports muscle recovery |
When to see a doctor: if you can’t gain weight despite eating a lot, or you’re losing weight unintentionally, get checked for conditions like an overactive thyroid, diabetes, or digestive disorders.
How To Improve Digestion?
Metabolism and digestion are connected, and healthy digestion helps you absorb nutrients and feel your best.
Eat More Fiber
Fiber is one of the most important nutrients for digestion, yet only about 5% of US adults meet daily recommendations.
Recommended intakes are 25 grams a day for women and 38 grams for men under 50, and 21 and 30 grams for those over 50.
Most Americans eat only about 17 grams a day.
| High-Fiber Food | Approximate Benefit |
|---|---|
| Lentils, beans, chickpeas | Very high fiber |
| Oats and barley | Soluble fiber |
| Whole grains | Pearled barley provides about 6 grams per cup vs under 2 grams in white rice |
| Berries and pears | Fiber-rich fruits |
| Vegetables | Fiber with few calories |
| Chia and flaxseeds | Concentrated fiber |
| Nuts | Fiber and healthy fats |
Tip: increase fiber gradually and drink more water to avoid gas and bloating. Some people also try supplements like Finessa digestive powder, but fiber and water should come first.
Other Ways To Improve Digestion
| Habit | Why It Helps |
|---|---|
| Drink enough water | Helps fiber work and prevents constipation |
| Eat slowly and chew well | Aids digestion |
| Move after meals | Supports gut movement |
| Manage stress | Stress affects the gut |
| Eat fermented foods (curd, yogurt, kefir) | May support healthy gut bacteria |
| Limit ultra-processed foods | Often low in fiber |
| Don’t overuse laxatives | Can disrupt normal bowel function |
When To See A Doctor About Digestion
| Symptom | Why It Matters |
|---|---|
| Blood in stool | Needs prompt evaluation |
| Unexplained weight loss | Can signal serious conditions |
| Persistent pain or bloating | May indicate a digestive disorder |
| Change in bowel habits lasting weeks | Should be checked |
| Difficulty swallowing | Needs medical evaluation |
| Ongoing heartburn | May need treatment |
A Simple Daily Plan For Better Metabolism And Digestion
| Time | Habit |
|---|---|
| Morning | Drink water; eat a protein-rich, high-fiber breakfast |
| Throughout the day | Move every 30 to 60 minutes |
| Meals | Include protein, vegetables, and whole grains |
| After meals | Take a short walk |
| 2 to 3 times a week | Strength training |
| Most days | 30 minutes of aerobic activity |
| Evening | Avoid heavy late meals |
| Night | Sleep 7 to 9 hours |
So, How Do You Improve Metabolism And Digestion?
Your metabolism is more stable than you might think, staying essentially unchanged from age 20 to 60 according to a major 2021 study.
The best ways to improve it are building muscle through strength training, eating enough protein, moving throughout the day, sleeping well, and avoiding crash diets that can lower your metabolic rate for years.
For digestion, eating more fiber, drinking enough water, and staying active make the biggest difference, especially since only about 5% of US adults get enough fiber.
Skip “metabolism booster” products with exaggerated claims, and if you’re considering a supplement, compare the cost of Finessa with cheaper options like psyllium.
See a doctor if you have persistent fatigue, unexplained weight changes, or ongoing digestive symptoms.
Frequently Asked Questions About Metabolism And Digestion
What Is Metabolism?
Metabolism is all the chemical processes your body uses to turn food into energy and keep you alive. It includes your resting metabolic rate, the energy used to digest food, and physical activity.
What Is BMR?
BMR, or basal metabolic rate, is the number of calories your body burns at rest to keep vital functions running. It makes up about 70% to 80% of daily calorie burn.
How Can I Increase My Metabolism Naturally?
Metabolism increases naturally with strength training, eating enough protein, moving throughout the day, sleeping well, and avoiding crash diets. Resistance training raised resting metabolism about 5% in one study.
Does Metabolism Slow Down With Age?
Metabolism stays stable from age 20 to 60 and declines about 0.7% per year after 60, according to a 2021 study of more than 6,400 people. It doesn’t drop sharply at 30.
What Foods Boost Metabolism?
Metabolism boosting foods are mainly high in protein, like eggs, fish, chicken, lentils, and yogurt. Protein uses 20% to 30% of its calories during digestion, compared with 0% to 3% for fat.
Do Metabolism Booster Supplements Work?
Metabolism booster supplements usually have small, temporary effects at best. They don’t replace exercise, protein, and healthy habits, and some contain stimulants or laxatives.
Can Dieting Slow Your Metabolism?
Metabolism can slow with severe dieting. Six years after The Biggest Loser, contestants burned about 500 fewer calories a day than expected for their size.
How Can Skinny Guys Gain Weight If Their Metabolism Is Fast?
Skinny guys can gain weight by eating more calorie-dense foods, eating more often, prioritizing protein, and strength training. You can’t safely slow your metabolism, but you can eat more.
How Can I Improve My Digestion?
Digestion improves with more fiber, enough water, regular movement, slower eating, and stress management. Only about 5% of US adults meet daily fiber recommendations.
When Should I See A Doctor About Metabolism Or Digestion?
Metabolism or digestion concerns need a doctor’s visit if you have unexplained weight changes, persistent fatigue, blood in your stool, or ongoing digestive symptoms. These may signal thyroid or digestive conditions.
References
- Pontzer, H., Yamada, Y., Sagayama, H., et al. (2021). Daily Energy Expenditure through the Human Life Course. Science, 373(6556), 808–812. Read the research study
- Peterson, M. D., Sen, A., & Gordon, P. M. (2011). Influence of Resistance Exercise on Lean Body Mass in Aging Adults: A Meta-Analysis. Medicine & Science in Sports & Exercise, 43(2), 249–258. Read the research study
- Fothergill, E., Guo, J., Howard, L., et al. (2016). Persistent Metabolic Adaptation 6 Years After “The Biggest Loser” Competition. Obesity, 24(8), 1612–1619. Read the research study
- Reicks, M., Jonnalagadda, S., Albertson, A. M., & Joshi, N. (2014). Total Dietary Fiber Intakes in the U.S. Population Are Low: The Latest NHANES Results. Read the research
- National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Energy. Read the energy expenditure reference
- U.S. Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd Edition. Read the physical activity guidelines