Covered by most extended health insurance with HSA plans.
Covered by most extended health insurance with HSA plans.
Metabolism is complex and multifactorial
Here are some insights into common issues our patients were experiencing
Why Weight Loss Can Stall — Even When You’re Doing Everything Right
Many people eat less, exercise more, and still struggle to lose weight. This is not always due to lack of effort or “willpower.” In some cases, the problem is something called metabolic suppression, also known as a “slow metabolism.” ¹ ²
What Is Metabolic Suppression?
Metabolic suppression happens when your body starts burning fewer calories than expected, even at rest. This can occur after long periods of dieting, eating too few calories, or losing weight repeatedly (yo-yo dieting).³
Normally, when we lose weight, our bodies burn fewer calories simply because we are smaller. But with metabolic suppression, the body burns even fewer calories than expected, making weight loss — or even maintaining weight — extremely difficult.³ ⁴
Why Does This Happen?
Your body is built to survive. When it senses you’re not getting enough food, it tries to protect you by conserving energy. It does this by:⁴ ⁵
Common Causes of a Slower Metabolism
Signs You May Have a Suppressed Metabolism
How Do You Know for Sure?
Most people use online calorie calculators — but these formulas can be wrong by 200–500 calories per day, especially if your BMI is 30 or more.⁸
At Thames Diagnostics, we measure your actual metabolic rate using indirect calorimetry — not just formulas — and we see metabolic suppression in about 10% of referred patients.
Why Metabolic Rate Testing Matters
✔ Shows if your metabolism is slower than expected
✔ Helps doctors and dietitians choose the right calorie target
✔ Helps prevent under-eating that can make metabolism worse
✔ Tracks metabolic recovery after weight loss
✔ Replaces guesswork with real numbers⁹ ¹⁰
Can You Fix a Suppressed Metabolism? Yes — With the Right Plan
Ways to help restore metabolic function include:
Why This Matters Even More for BMI ≥ 30
If your BMI is 30 or more:
Final Takeaway
References
Rosenbaum M, Leibel RL. Adaptive thermogenesis in humans. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023.
https://www.ncbi.nlm.nih.gov/books/NBK560523/
At Thames Diagnostics we measure patients' resting or basal metabolic rate.
Patients often ask us how they can increase their resting metabolic rate. Given our focus on measuring, we advise patients to follow up with their health provider. However, with the question arising so often our curiosity got the better of us and we embarked on the task to find an answer. Here is what we found.
Why RMR Matters
Your resting metabolic rate (RMR) is the number of calories your body uses at rest just to stay alive — for breathing, heart function, brain activity, and temperature regulation.
For people living with overweight or obesity, safely supporting or restoring RMR is not about “boosting metabolism overnight,” but rather:
✔ Preserving muscle
✔ Avoiding metabolic suppression from crash dieting
✔ Setting calorie goals based on measured, not estimated, values
Important Note:
Most strategies lead to modest changes (often tens to a few hundred calories per day). But when combined properly — especially with muscle preservation and accurate RMR measurement — they lead to safer, more successful weight loss.
How to read this list:
• Ordered from smallest average effect on RMR (or RMR protection) → largest.
• Each item shows Comparative Effectiveness (impact on RMR/protection) and Practicality (how doable it is for most people).
• Individual responses vary. The biggest, most durable gains come from adding lean mass and avoiding metabolic suppression.
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1) Caffeine / Green-Tea Catechins (small, short-term boost)
Effectiveness: ★★☆☆☆ Practicality: ★★★★☆
Why: Caffeine (and caffeine + green-tea catechins) can raise daily energy expenditure a little (~3–4% in studies), largely via thermogenesis. Effects vary and may wane with habitual use. Not a primary driver of RMR, but a modest adjunct.”Net 24-h impact can be smaller in free-living settings due to tolerance and compensation. [13,14]
How: If you tolerate it and your clinician agrees, use moderate coffee/tea intake. Avoid if pregnant, anxious, hypertensive, or sensitive to stimulants.
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2) Mild Cold Exposure (specialised; start cautiously)
Effectiveness: ★★☆☆☆ Practicality: ★★☆☆☆
Why: Repeated, tolerable cold exposure may recruit brown adipose tissue and nudge energy expenditure up. Practicality and comfort limit use. Prioritise higher-yield strategies first. [17]
How: Only if cleared by your clinician: brief cool environments or cool-water finishes; stop if uncomfortable.
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3) Sleep Optimisation & Stress Management (protects RMR; improves appetite control)
Effectiveness: ★★☆☆☆ (protection) Practicality: ★★★★☆
Why: Short sleep and chronic stress disrupt appetite hormones and can reduce spontaneous activity; some data show poorer fat-loss quality and potential drops in expenditure during calorie restriction. Protects RMR more than it “raises” it. Primary benefit is preservation of energy expenditure and adherence; direct RMR increases are unlikely. [15,16]
How: Aim for 7–9 hours, regular sleep/wake times, limit late caffeine, use stress-reduction skills (breathing, CBT-style tools, brief activity breaks). Note that very high volumes with large calorie deficits can sometimes reduce RMR via suppression—so pairing with protein and measured fueling is key.
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4) Smart Aerobic/HIIT as an Adjunct (supports energy flux; protects lean mass)
Effectiveness: ★★☆☆☆ (indirect) Practicality: ★★★★☆
Why: Cardio is excellent for heart health and helps maintain a higher daily energy flux. On its own, it has limited direct effect on RMR compared with strength training, but it supports lean-mass preservation when calories and protein are adequate. [18]
How: 150–300 min/week moderate aerobic (or 75–150 min vigorous); add 1–2 short HIIT sessions if appropriate.
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5) Creatine Monohydrate (with strength training)
Effectiveness: ★★☆☆☆–★★★☆☆ (via lean mass) Practicality: ★★★★☆
Why: Creatine supports training performance and lean-mass gains in many adults, indirectly supporting RMR. One of the most studied, generally safe supplements when used as directed. [12]
How: Typical: 3–5 g/day (or a brief loading phase then 3–5 g/day). Discuss with your clinician if you have kidney disease or take nephroactive medicines; stay hydrated.
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6) Treat Medical Contributors (e.g., hypothyroidism, iron deficiency, sleep apnoea)
Effectiveness: ★★★☆☆ (when present) Practicality: ★★★★☆
Why: Overt hypothyroidism lowers RMR; appropriate thyroid hormone replacement restores it. Iron deficiency, chronic inflammation and untreated obstructive sleep apnoea can worsen fatigue/energy balance; apnoea treatment improves cardiometabolic health with mixed but promising effects on expenditure. [10,11]
How: Ask your clinician about testing when symptoms suggest a medical driver (thyroid, anaemia, snoring/apnoeas/daytime sleepiness).
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7) Avoid Crash Diets; Use Moderate Calorie Deficits (prevents metabolic suppression)
Effectiveness: ★★★★☆ (protection) Practicality: ★★★★☆
Why: Very-low-calorie or “crash” diets trigger adaptive thermogenesis (metabolic suppression) that can persist. Moderate, sustainable deficits reduce this response, preserving RMR and adherence. [5,6]
How: If possible, base targets on measured RMR. A common starting point is a ~15–25% reduction from needs, with regular reassessment to avoid under-fueling.
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8) Higher-Protein Intake (≈ 1.2–1.6 g/kg/day)
Effectiveness: ★★★★☆ Practicality: ★★★★☆
Why: Protein has the largest thermic effect of food and strongly helps preserve/build lean mass during weight loss, limiting the RMR drop seen with dieting. Distributing protein across meals supports muscle protein synthesis. [3,4]
How: Target 1.2–1.6 g/kg/day (adjust for kidney health and clinician advice). Use lean meats, fish, eggs, dairy/fortified alternatives, legumes, tofu/tempeh; quality protein supplements when appropriate.
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9) Progressive Resistance Training (the cornerstone for raising RMR)
Effectiveness: ★★★★★ Practicality: ★★★★☆
Why: Adding or preserving muscle is the most reliable way to push RMR upward and keep it there. Trials show higher daily energy expenditure and free-living activity after consistent resistance training, especially in older adults. [1,2]
How: 2–3 sessions/week; train all major muscle groups; 2–4 sets of 6–12 controlled reps; gradually increase load/volume (progressive overload). Pair with adequate protein (and consider creatine) for best results.
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10) Personalise with Indirect Calorimetry (measure, don’t guess)
Effectiveness: ★★★★★ (as an enabler: avoids suppression, makes every step work better) Practicality: ★★★★★
Why: In adults with BMI ≥30, prediction equations often overestimate RMR, leading to calorie targets that are too high or (paradoxically) to over-restriction and suppression. Measuring your RMR with indirect calorimetry lets you set the right calories, catch suppression early, and adjust in real time. [7–9]
How (at Thames Diagnostics):
• Test baseline RMR.
• Re-check after initial weight loss and during maintenance.
• Use results to fine-tune calories, protein and training so you preserve lean mass and protect (or raise) RMR.
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Quick Safety Notes
• Check with your clinician before starting supplements, cold exposure, or new training—especially if you have heart, kidney, thyroid, sleep or mental-health conditions, or if you’re pregnant.
• Bigger, safer improvements come from muscle-centred plans (strength training + protein), measured calorie targets, and avoidance of crash diets.
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References (Vancouver style, hyperlinked)
1. Hunter GR, Wetzstein CJ, Fields DA, Brown A, Bamman MM. Resistance training increases total energy expenditure and free-living physical activity in older adults. J Appl Physiol. 2000;89(3):977–984. https://doi.org/10.1152/jappl.2000.89.3.977
2. Speakman JR, Selman C. Physical activity and resting metabolic rate. Proc Nutr Soc. 2003;62(3):621–634. https://doi.org/10.1079/PNS2003282
3. Leidy HJ, Clifton PM, Astrup A, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015;101(6):1320–1329. https://doi.org/10.3945/ajcn.114.084038
4. Westerterp KR. Diet induced thermogenesis. Nutr Metab (Lond). 2004;1:5. https://doi.org/10.1186/1743-7075-1-5
5. Dulloo AG, Montani JP, Schutz Y. Adaptive thermogenesis in resistance to obesity therapies: issues, controversies and future directions. Int J Obes. 2021;45(9):1977–1988. https://doi.org/10.1038/s41366-021-00878-6
6. Fothergill E, Guo J, Howard L, et al. Persistent metabolic adaptation 6 years after “The Biggest Loser” competition. Obesity (Silver Spring). 2016;24(8):1612–1619. https://pubmed.ncbi.nlm.nih.gov/27136388/
7. Frankenfield DC, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775–789. https://pubmed.ncbi.nlm.nih.gov/15883556/
8. Delsoglio M, Achamrah N, Berger MM, Pichard C. Indirect calorimetry in clinical practice. J Clin Med. 2019;8(9):1387. https://doi.org/10.3390/jcm8091387
9. Achamrah N, et al. Can indirect calorimetry help tailor metabolic needs after weight changes? Clin Nutr. 2021;40(1):4–10. https://doi.org/10.1016/j.clnu.2020.07.007
10. Mullur R, Liu YY, Brent GA. Thyroid hormone regulation of metabolism. Physiol Rev. 2014;94(2):355–382. https://doi.org/10.1152/physrev.00030.2013
11. Aronson D, et al. Obstructive sleep apnoea and energy metabolism. Prog Cardiovasc Dis. 2009;51(5):414–423. https://doi.org/10.1016/j.pcad.2008.11.003
12. Candow DG, Chilibeck PD, Forbes SC. Creatine supplementation and aging musculoskeletal health. J Cachexia Sarcopenia Muscle. 2019;10(6):1196–1212. https://doi.org/10.1002/jcsm.12468
13. Dulloo AG, Duret C, Rohrer D, et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation. Am J Clin Nutr. 1999;70(6):1040–1045. https://doi.org/10.1093/ajcn/70.6.1040
14. Hursel R, Westerterp-Plantenga MS. Catechin- and caffeine-rich teas for control of body weight in humans. Am J Clin Nutr. 2013;98(6 Suppl):1682S–1693S. https://doi.org/10.3945/ajcn.113.058396
15. Nedeltcheva AV, Kilkus JM, Imperial J, et al. Sleep curtailment is accompanied by increased intake of calories from snacks. Am J Clin Nutr. 2009;89(1):126–133. https://doi.org/10.3945/ajcn.2008.26574
16. Nedeltcheva AV, et al. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153(7):435–441. https://doi.org/10.7326/0003-4819-153-7-201010050-00006
17. Yoneshiro T, Aita S, Matsushita M, et al. Recruited brown adipose tissue as an anti-obesity agent in humans. J Clin Invest. 2013;123(8):3404–3408. https://doi.org/10.1172/JCI67803
18. Willis LH, Slentz CA, Bateman LA, et al. Effects of aerobic vs resistance training on visceral and liver fat. J Appl Physiol. 2012;113(12):1831–1837. https://doi.org/10.1152/japplphysiol.01370.2011
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Because equations can overestimate RMR in adults with BMI ≥30, we use indirect calorimetry to measure your true metabolic rate, so you can personalise calorie, protein and training targets. That’s how you raise (or protect) RMR safely—and keep progress sustainable.