There is a rather strong link between diet and metabolism! Even more so than genetics, diet directly impacts metabolic function in addition to other variables like lean muscle mass and sleep.
But because cells break down the food we provide them to use as their own fuel, one could argue that diet makes the biggest impact on maintaining a high metabolism.
Find out which foods, nutrients, and dietary patterns exert the best metabolic maintenance in this article.
Review of Metabolism
Recall that metabolism refers to the chemical (metabolic) reactions the body performs to sustain basic life functions like breathing, heart rate, circadian rhythm, and appetite. It is largely regulated by the endocrine system including the pituitary gland and thyroid.
Examples of metabolic reactions include:
• Rebuilding muscle tissue after a workout
• Lowering cortisol levels in the evening to prepare for sleep
• Maintaining enough thyroid hormone production
• Shuttling glucose into cells via insulin
Metabolic reactions are anabolic or catabolic in nature. Anabolism refers to building and growing reactions and catabolism means breaking down and oxidizing.
Various factors like age, diet, and exercise impact metabolism. Uncontrollable factors are age, height, (body weight), and genetics to some extent, while controllable factors include (body weight), diet, exercise, lean body mass, sleep, and hydration.
Set Point Theory
Some people (even some health professionals) will argue that genetics mostly determine metabolism and that the slowing of it is inevitable.
To some extent, achieving a metabolism as high one in high school isn’t possible. Everyone does possess a genetically determined set point weight range.
This means the body has innate mechanisms that aim to keep a healthy, fully grown, and developed adult within a pretty tightly controlled range of weights. Science cannot yet fully explain which factors determine this.
However, set point theory is frequently overridden, as evidenced by the high rates of obesity today. Chronically overconsuming energy (calories) leads to fat storage and can release inflammatory cytokines (molecules) and shift a person above their innate set point. This mechanism is exacerbated by poor lifestyle habits like excessive alcohol intake and limited physical activity.
Interestingly, eating more calories does not technically slow metabolism. In fact, it increases metabolism! However, this isn’t to encourage frequent binge eating or eating inappropriate portions. Large amounts of weight gain can directly disrupt organ function, which then impacts metabolic functions much more severely.
On the other hand, eating too few calories slows metabolism! Underfueling teaches the body how to rely on fewer calories and over time, it adapts to slowing energy expenditure. Plus, studies show a paradoxical phenomenon, where those who reintroduce calories back after slowing their metabolism generally gain more weight and heighten their innate set point.
All in all, while the body possesses some innate mechanisms that regulate metabolism, it’s not the whole picture. As mentioned, diet plays an even larger role!
Diet and Metabolism
The quantity of your diet (caloric intake) matters some, but the quality of food you consume matters much more. Our cells directly use the nutrients we provide them from food to conduct metabolic reactions. The higher the quality food, the higher metabolic function will remain.
Everyone wants to know which foods boost metabolism most – looking at you celery and chili peppers – but a better question is which food groups help maintain a high metabolism. Spoiler alert, no single food is metabolic magic…
Foods and Metabolism
In general, protein-rich foods boost metabolism most because they are most thermogenic. Meaning, breaking down protein into amino acids requires the most energy and creates the most heat.
Conversely, simple carbohydrates (anything that’s not a fruit, vegetable, bean, legume, or whole grain) require the least amount of energy to digest and create the least amount of heat. Thus, they tend to boost metabolism least, unless the body needs glucose, in which case feeding carbohydrates would speed up metabolic reactions.
Fat lies in the middle of protein and carbs in terms of boosting metabolism. It takes the longest to break down, therefore, requires more fuel than carbohydrates. But since it can be stored as body fat rather than needing to be converted into a completely different molecule like protein, it still reigns second.
Additionally, anti-inflammatory foods bolster metabolism while pro-inflammatory foods harm or slow metabolic functions.
Food groups that may increase metabolism and burn fat:
• Fruits and vegetables because of their antioxidants, fiber content, and other phytochemicals
• Beans and legumes because of their fiber content and phytochemicals
• Wild-caught seafood because of their omega-3 fatty acids and antioxidants
• High-quality, grass-fed meat because of their vitamins, minerals and protein content
• Healthy fats like olive oil, avocado, nuts and seeds because of their fiber, vitamin, and mineral profile
• Spices and herbs like cinnamon, turmeric, black pepper, cilantro, parsley and basil because of unique properties
Food groups that may slow metabolism:
• Added sugars in packaged and processed foods
• Hydrogenated and refined vegetable oils
• Trans fat in processed and packaged foods
• Low-quality protein like conventionally raised meat
• Fried, greasy foods
• Refined carbohydrates like white bread and pasta, pastries, etc.
Nutrients that Might Help Boost Metabolism
Perhaps as important as the overall diet is optimizing certain micro and functional nutrients. Macronutrients (carbs, fat, protein) are important because they directly provide fuel for cells, but micronutrients act as vital cofactors, enzymes, chemical messengers, and hormones for cells.
In essence, micronutrients spur the metabolic reactions that eventually allow cells to break down food into usable energy and maintain organ and gland function.
While all micronutrients are important, some are more connected to metabolism, mostly because they directly impact the thyroid and pituitary, which are the master regulators of metabolism.
Some people can obtain sufficient micronutrients from diet alone, but many need to take a multivitamin to bridge nutritional gaps.
The most vital nutrients to optimize for good thyroid health and therefore metabolism are:
This mineral is vital because the thyroid directly uses selenium to produce selenoproteins. Selenium deficiency is highly associated with an underactive thyroid and autoimmune Hashimotos thyroiditis. Fun fact - you can obtain 100% of selenium needs by eating 2 to 3 brazil nuts per day!
Other high selenium foods include:
• Tuna, cod, and other seafood
• Chicken, turkey, beef, and organ meats
• Sunflower seeds
• Whole grains
Similar to selenium, the thyroid needs just enough iodine to produce the major thyroid hormones T3 and T4, and deficiency but also too much iodine is linked with decreased thyroid function. Nearly every single cell in the human body possesses receptors for thyroid hormones, highlighting how thoroughly the thyroid regulates metabolic reactions.
Unfortunately, not many foods are high in iodine besides iodized salt, seaweed, and some seafood. It’s still important to monitor overall sodium intake, though, as that can lead to problems that reduce thyroid and metabolic function.
Enjoy a mixture of high-quality sea salt in addition to some iodized table salt to optimize iodine.
Another important mineral, iron is more well known for its role in red blood cell production and oxygen transport. Just like our muscles need oxygen to contract properly, the thyroid needs enough iron and oxygen to execute its functions.
Despite several common foods including iron, deficiency is still pretty common, especially amongst vegetarians and vegans, the elderly, those who lose a lot of blood, and athletes.
Some plant foods such as leafy greens, beans and legumes, fortified grains and some fruits have higher iron content, but it’s less absorbable than animal sources:
• Organ meats
• Grass-fed meat
This unique trace mineral helps regulate works closely with iron to make red blood cells and keeps blood vessels, nerves bones, and the immune system healthy. Because it’s a trace mineral, daily requirements aren’t high, but it’s still important to get enough:
• Beef liver and other organ meats
• Whole grains, beans and legumes
• Hazelnuts, almonds, peanuts
• Black pepper, cocoa and prunes
This vital mineral and electrolyte is involved in the most amount of metabolic reactions of all the nutrients! Despite this, many Americans are deficient in magnesium, which directly slows metabolism.
Different forms of magnesium exert different functions, so it’s important to eat a variety of foods high in magnesium.
• Beans and legumes
• Sunflower and other seeds, cashews, almonds
• High-quality whole grains
Like magnesium, all the B vitamins are involved in numerous metabolic reactions, especially the ones that break down food into energy. Obviously, this direct connection with metabolism makes deficiencies of any B vitamins problematic. B6 and B12 tend to be the most common deficiencies and result in extreme lethargy among other symptoms.
Additionally, many people have a genetic mutation (MTHFR) that depletes folate. Thus, it’s wise to take a high-quality multivitamin or B-complex with methylated folate in addition to consuming:
• Pork, beef, poultry, eggs, seafood, organ meats, and dairy
• Fortified whole grains and cereals, brown rice, and quinoa
• Beans and legumes
• Green vegetables, tomatoes, mushrooms, potatoes, and soy
• Non-citrus fruits
Well known for its immune-boosting properties, this is why it’s important to maintain a high metabolism! A decreased immune system causes inflammation that reduces cellular function.
Get enough of this beneficial mineral from:
• Beef, poultry, seafood (especially oysters)
• Fortified whole grains and cereals
Fiber & Antioxidants
What do these two powerhouse groups of nutrients have in common? They are both prominent in vibrantly colored plant foods, which contain substances called phytonutrients that supply extra benefit in addition to vitamins and minerals.
The benefits of fiber and antioxidants are endless. In terms of metabolism, they both help keep inflammation at bay, balance blood sugar and make it easier for cells to respond to stress.
Balance your diet with these fiber and antioxidant-rich foods:
• Veggies - the darker the color, the more potent antioxidants
• Fruits with skin and seeds - berries, citrus fruits, apples, and pears are highest in fiber
• Avocados - very high in fiber and also serves as a healthy fat source
• Olive oil - a potent antioxidant and improve lipid profile (cholesterol and triglycerides)
• Coffee and green tea - specific antioxidant properties
• Beans, legumes, and whole grains - different kinds of fiber than fruits and veggies
Finally, there are other types of ‘nutrients’ that help maintain a high metabolism because they balance hormones and generally adapt to what the body needs. For example, those under high stress can benefit from a mushroom called Reishi to balance cortisol production.
Some of these nutrients act directly on the thyroid while others benefit systems involved with the thyroid and other metabolic regulators like the adrenals.
• Adaptogens - ashwagandha, rhodiola, maca, holy basil, and many more
• Mushrooms - reishi, cordyceps, lion’s mane, shitake, and maitake
The Bottom Line
Metabolism is heavily impacted by diet. In fact, diet likely plays the biggest role in determining one's metabolic rate throughout adulthood.
Eating just enough calories is important, as undereating slows metabolism and chronically overeating burdens cells and can cause health problems that then slow metabolism.
Antiinflammatory diets like the Mediterranean diet, high-quality protein, and colorful, high-fiber foods greatly bolster metabolic function. Proinflammatory foods like trans fat, refined carbs, added sugar, and some saturated fats weaken cells and decrease metabolism.
Finally, prioritize micronutrients like selenium, iron, magnesium, and fiber to sustainably maintain a high metabolic rate!
Kubala, J. Supplements and thyroid health: What to know. Healthline. Written December 23, 2020. https://www.healthline.com/nutrition/thyroid-vitamins.
Raman, R. Best diet for hypothyroidism. Healthline. Updated June 17, 2021. https://www.healthline.com/nutrition/hypothyroidism-diet#foods-to-avoid.
Shomon, M. What to know about selenium and your thyroid. Verywell Health. https://www.verywellhealth.com/selenium-and-your-thyroid-4134998.