Metabolism Assessment Checklist

Metabolism Myths Debunked: 5 Eye-Opening Truths You Need to Know

Metabolism is a complex process that often gets oversimplified. Many believe that specific actions like exercise or eating at certain times can drastically change how our bodies burn calories. But how much of this is true? Let's debunk some common myths about metabolism and explore its complex relationship with nutrition and exercise.


What is Metabolism?

Metabolism is the chemical reaction in every cell that harnesses energy to keep us alive. These processes include making new cells, growing hair, and converting food into energy. The total energy of these processes is measured in calories.


Myth 1: Exercise Dramatically Boosts Metabolism

Many believe exercise significantly boosts metabolism. However, exercise accounts for a small percentage of daily calorie burn unless you're a professional athlete. Most calorie expenditure comes from your basal metabolic rate (BMR: the number of calories your body burns at rest to maintain basic functions), which includes vital functions like maintaining a heartbeat, growing hair, building cells, and even blinking.

That said, exercise does contribute to calorie burn in essential ways. High-intensity exercises, like running or cycling, burn more calories per minute than lower-intensity activities. Strength training, like lifting weights, builds muscle mass. More muscle mass can slightly increase your BMR over time, as muscle tissue burns more calories at rest than fat tissue. However, research by Herman Pontzer, an evolutionary anthropologist who studies hunter-gatherer populations like the Hadza tribe in Tanzania, suggests our bodies are efficient and may compensate for increased exercise by reducing energy use in other areas to maintain overall calorie expenditure. Therefore, while cardio and strength training benefits overall health and calorie expenditure, they do not dramatically boost your metabolism as many believe.


The Hadza Study: A Closer Look

Researchers studied the Hadza people of Tanzania, who live a traditional hunter-gatherer lifestyle, to understand metabolism better. Evolutionary anthropologist Herman Pontzer's work with the Hadza involved using doubly labeled water (a type of water used by scientists to measure how many calories someone burns) to track their daily energy expenditure. Despite their active lifestyle, when controlling for body size and age, the Hadza burn a similar number of calories daily as an average American adult. This study shows that calorie expenditure is relatively fixed, and our bodies have limits on how much energy they can burn. It highlights that even with increased physical activity, there are biological constraints on calorie burning, underscoring the importance of nutrition and overall lifestyle in managing metabolism.


Myth 2: Thinner People Have Faster Metabolisms

It's a common belief that thinner people naturally have faster metabolisms, but this isn't necessarily true. Metabolism varies significantly from person to person due to genetics and body composition. In fact, people with larger bodies often have faster metabolisms because they burn more calories to sustain a more significant number of cells, especially if they have more muscle mass (the amount of muscle tissue in their body).


While larger bodies burn more calories to sustain themselves due to more cells, muscle mass is a more significant factor influencing metabolic rate. Individuals with higher muscle density require more energy for daily activities, regardless of their overall body size. This higher energy requirement can create the impression of a faster metabolism. So, while it may seem like thinner people have faster metabolisms, the reality is that muscle mass and density are more significant factors in determining metabolic rate.


Myth 3: Eating Small, Frequent Meals Boosts Your Metabolism


There's a widespread belief that eating small, frequent meals throughout the day can keep your metabolism running high and aid in weight loss. However, the frequency of meals has little effect on overall metabolic rate. What matters most is the total number of calories consumed and the nutritional quality of those calories.


Research shows that the total calorie burn remains roughly the same whether you eat three larger meals or six smaller ones. The key is to find an eating pattern that works best for your body and lifestyle, ensuring it supports your nutritional needs and helps you maintain a healthy weight.


Myth 4: Eating Late at Night Slows Down Your Metabolism


Many believe eating late at night can slow your metabolism and lead to weight gain. However, the timing of your meals has little impact on your metabolic rate. What matters more is the type of food you eat and the total calories consumed.


Nutrition plays a crucial role in managing metabolism. The foods we eat fuel our metabolic processes, and balanced nutrition, emphasizing whole foods, helps ensure these processes run efficiently. Protein and fiber are essential for weight management. Protein helps you feel fuller for longer, potentially reducing cravings. Fiber can also promote satiety and slow digestion.


Note: While the timing of your meals doesn't directly affect metabolism, eating late at night can disrupt your sleep, mainly if the meal is high in refined carbohydrates or fats. Poor sleep quality can negatively impact your overall health and contribute to weight gain.


Myth 5: Exercise Only Affects Muscle Metabolism


Exercise may not drastically boost overall energy expenditure. Still, it profoundly benefits your body's overall metabolism. Regular exercise improves how your body uses energy in organs like the liver, fat tissue (adipose tissue), blood vessels (vasculature), and the pancreas. This is crucial for reducing the risk of metabolic diseases such as type 2 diabetes and non-alcoholic fatty liver disease. Exercise triggers adaptations in these tissues, supported by signaling molecules and hormones known as 'exerkines,' such as irisin, which helps regulate fat burning.


The key takeaway: While exercise helps your muscles burn calories, it also benefits your entire body's ability to use energy efficiently, keeping you healthy and energized.


The Upshot


Our metabolic system's primary function is to manage energy efficiently, not to control weight. When you come across claims to "boost your metabolism" for weight loss, remember that this is often marketing rooted in weight loss culture. The science doesn't support these claims.


Forget about quick fixes and magic bullets! Understanding metabolism empowers you to make informed choices about nourishing and moving your body. Exercise remains a cornerstone of health, but focus on its numerous benefits, like improved cardiovascular health and stronger muscles.


Building a sustainable, balanced approach is critical. This means incorporating regular physical activity, prioritizing a nutritious diet rich in whole foods, and adopting healthy lifestyle habits. By separating fact from fiction about metabolism, you can cultivate a deeper appreciation for this intricate system that fuels your body. This knowledge empowers you to make informed decisions that support your long-term health, fitness, and nutritional goals.


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Sources and Further Reading

McPherron AC, Guo T, Bond ND, Gavrilova O. Increasing muscle mass to improve metabolism. Adipocyte. 2013 Apr 1;2(2):92-8. doi: 10.4161/adip.22500. PMID: 23805405; PMCID: PMC3661116.


Cameron JD, Cyr MJ, Doucet E. Increased meal frequency does not promote greater weight loss in subjects who were prescribed an 8-week equi-energetic energy-restricted diet. Br J Nutr. 2010 Apr;103(8):1098-101. doi: 10.1017/S0007114509992984. Epub 2009 Nov 30. PMID: 19943985.


Calcagno M, Kahleova H, Alwarith J, Burgess NN, Flores RA, Busta ML, Barnard ND. The Thermic Effect of Food: A Review. J Am Coll Nutr. 2019 Aug;38(6):547-551. doi: 10.1080/07315724.2018.1552544. Epub 2019 Apr 25. PMID: 31021710.


Salleh SN, Fairus AAH, Zahary MN, Bhaskar Raj N, Mhd Jalil AM. Unravelling the Effects of Soluble Dietary Fibre Supplementation on Energy Intake and Perceived Satiety in Healthy Adults: Evidence from Systematic Review and Meta-Analysis of Randomised-Controlled Trials. Foods. 2019 Jan 6;8(1):15. doi: 10.3390/foods8010015. PMID: 30621363; PMCID: PMC6352252.


Thyfault JP, Bergouignan A. Exercise and metabolic health: beyond skeletal muscle. Diabetologia. 2020 Aug;63(8):1464-1474. doi: 10.1007/s00125-020-05177-6. Epub 2020 Jun 11. PMID: 32529412; PMCID: PMC7377236.


Pontzer H, Raichlen DA, Wood BM, Emery Thompson M, Racette SB, Mabulla AZ, Marlowe FW. Energy expenditure and activity among Hadza hunter-gatherers. Am J Hum Biol. 2015 Sep-Oct;27(5):628-37. doi: 10.1002/ajhb.22711. Epub 2015 Mar 30. PMID: 25824106.


McNab BK. What determines the basal rate of metabolism? J Exp Biol. 2019 Aug 6;222(Pt 15):jeb205591. doi: 10.1242/jeb.205591. PMID: 31262787.


Argilés JM, Campos N, Lopez-Pedrosa JM, Rueda R, Rodriguez-Mañas L. Skeletal Muscle Regulates Metabolism via Interorgan Crosstalk: Roles in Health and Disease. J Am Med Dir Assoc. 2016 Sep 1;17(9):789-96. doi: 10.1016/j.jamda.2016.04.019. Epub 2016 Jun 17. PMID: 27324808.


Westcott WL. Resistance training is medicine: effects of strength training on health. Curr Sports Med Rep. 2012 Jul-Aug;11(4):209-16. doi: 10.1249/JSR.0b013e31825dabb8. PMID: 22777332.


Pontzer H, Yamada Y, Sagayama H, Ainslie PN, Andersen LF, Anderson LJ, Arab L, Baddou I, Bedu-Addo K, Blaak EE, Blanc S, Bonomi AG, Bouten CVC, Bovet P, Buchowski MS, Butte NF, Camps SG, Close GL, Cooper JA, Cooper R, Das SK, Dugas LR, Ekelund U, Entringer S, Forrester T, Fudge BW, Goris AH, Gurven M, Hambly C, El Hamdouchi A, Hoos MB, Hu S, Joonas N, Joosen AM, Katzmarzyk P, Kempen KP, Kimura M, Kraus WE, Kushner RF, Lambert EV, Leonard WR, Lessan N, Martin C, Medin AC, Meijer EP, Morehen JC, Morton JP, Neuhouser ML, Nicklas TA, Ojiambo RM, Pietiläinen KH, Pitsiladis YP, Plange-Rhule J, Plasqui G, Prentice RL, Rabinovich RA, Racette SB, Raichlen DA, Ravussin E, Reynolds RM, Roberts SB, Schuit AJ, Sjödin AM, Stice E, Urlacher SS, Valenti G, Van Etten LM, Van Mil EA, Wells JCK, Wilson G, Wood BM, Yanovski J, Yoshida T, Zhang X, Murphy-Alford AJ, Loechl C, Luke AH, Rood J, Schoeller DA, Westerterp KR, Wong WW, Speakman JR; IAEA DLW Database Consortium. Daily energy expenditure through the human life course. Science. 2021 Aug 13;373(6556):808-812. doi: 10.1126/science.abe5017. PMID: 34385400; PMCID: PMC8370708.