The Claim
During 180 minutes of submaximal endurance exercise at 64% VO2max, ultra-endurance runners on a long-term low-carbohydrate diet exhibit a 59% higher mean fat oxidation rate (1.21 g/min) compared to those on a high-carbohydrate diet (0.76 g/min), with fat contributing 88% of energy expenditure versus 56% in the high-carbohydrate group.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
Ultra-endurance runners who follow a long-term low-carbohydrate diet burn fat at a rate 59% higher during 180 minutes of steady endurance exercise at 64% of their maximum oxygen uptake, and derive 88% of their energy from fat, compared to runners on a high-carbohydrate diet who derive 56% of their energy from fat.
See the scientific wording
During 180 minutes of submaximal endurance exercise at 64% VO2max, ultra-endurance runners on a long-term low-carbohydrate diet sustain a 59% higher mean fat oxidation rate (1.21 g/min) compared to those on a high-carbohydrate diet (0.76 g/min), with fat contributing 88% of energy use versus 56% in the high-carbohydrate group.
When the body is used to burning fat for fuel over a long time, it builds more mitochondria and turns on enzymes that break down fat, allowing it to use fat as the main energy source during long exercise without needing sugar.
What the research says
1 studyStudy: Metabolic characteristics of keto-adapted ultra-endurance runners.
When ultra-runners eat very low-carb for months, their bodies get really good at burning fat during long runs — they burn nearly 60% more fat per minute and get almost 90% of their energy from fat, compared to runners who eat lots of carbs.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.