Research
Energy balance
High-intensity exercise (>75% VO2max) limits fat oxidation due to a depletion of free carnitine, which is consumed to buffer excess acetyl-CoA from glycolysis, thereby restricting fatty acid transport into the mitochondria.
Avoid high-intensity exercise if your primary goal is to maximize fat oxidation per minute. At intensities above 75% VO2max, your body prioritizes carbohydrates, and a lack of free carnitine prevents fat from being used as fuel. Stick to moderate intensities for better fat burning efficiency.
GoodRefutesHIGH confidence
During high intensity exercise however, large quantities of acetyl-CoA are also produced via fast glycolysis which enter the mitochondrial matrix and supersede TCA cycle utilization... free carnitine is used to buffer excess glycolytic derived acetyl-CoA by forming acetyl-carnitine... and therefore the limited concentration of free carnitine is a rate limiting step in FA transport/oxidation
Why this rating
Well-established biochemical mechanism cited in the review.
Source
Understanding the factors that effect maximal fat oxidation
Troy Purdom et al. · Journal of the International Society of Sports Nutrition · 2018
DOI 10.1186/s12970-018-0207-1
narrative_reviewCited 235×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Maximal fat oxidation (MFO) occurs at exercise intensities between 45% and 65% of VO2max, with rates ranging from 0.17 to 1.27 g/min in trained individuals, and can exceed 1.5 g/min in ketogenic-adapted individuals.Good
- Endurance training increases maximal fat oxidation (MFO) rates and shifts the intensity at which MFO occurs to higher workloads by upregulating cellular transport proteins (CD36, CPT-1) and mitochondrial enzymes (HAD, Citrate Synthase).Good
Related findings · Energy balance
- Achieving a total body weight loss of 10-15% (or >10-15 kg) through Total Diet Replacement (TDR) induces remission of Type 2 Diabetes in individuals with short-duration disease.Strong
- Bariatric surgery is superior to medical management alone for inducing significant long-term weight loss, remission of type 2 diabetes, and reduction in mortality for patients with BMI ≥ 40 or ≥ 35 with comorbidities.Strong
- Achieving type 2 diabetes remission requires significant weight loss (≥15 kg) via major caloric restriction, independent of macronutrient composition.Strong
This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →