Research
Mixed
High fat diets increase the contribution of fat to oxidative metabolism at the same relative exercise intensity, raising the crossover point, but may initially decrease endurance performance by lowering muscle glycogen.
Eating a high-fat diet trains your body to burn more fat, allowing you to exercise at higher intensities without depleting sugar stores as fast. However, because your sugar stores are lower, you might feel weaker initially. Long-term adaptation may improve endurance at moderate intensities.
GoodQualifiesHIGH confidence
A number of studies have shown that eating a high fat diet for prolonged periods markedly increases the contribution of fat to oxidative metabolism at the same relative exercise intensity.
Why this rating
Cited studies support the mechanism, though the paper notes it is counterproductive for glycogen stores.
Source
The regulation of carbohydrate and fat metabolism during and after exercise
John O. Holloszy · Frontiers in bioscience · 1998
DOI 10.2741/a342
narrative_reviewCited 177×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Endurance exercise training increases muscle GLUT4 protein content and mitochondrial density, which shifts substrate utilization toward fat oxidation and spares muscle glycogen during sustained exercise.Strong
- Increasing relative exercise intensity shifts fuel utilization from fat to carbohydrate, with carbohydrate becoming the predominant fuel source above the 'crossover point' (typically ~50% VO2max in untrained individuals).Strong
Related findings · Mixed
- Bariatric surgery (VSG and RYGB) is the most effective and sustainable treatment for obesity, producing marked and sustained weight loss that non-surgical interventions cannot match.Strong
- Severely protein-deficient diets (2–3% energy) induce lean body mass loss and metabolic imbalance, whereas adequate protein intake (0.66 g/kg/d minimum) is a prerequisite for maintaining muscle, bone, and physiological function.Strong
- For patients with Class III obesity (BMI >39.9 kg/m2), metabolic bariatric surgery (MBS) is significantly more effective than any currently approved medication, with BilioPancreatic Diversion (BPD) showing the highest estimated weight loss.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 →