Research
Macro partitioning
Training in a low carbohydrate state ('train low') may improve fat oxidation pathways but reduces the ability to generate maximal power and may negatively affect race outcomes in high-intensity situations.
If you try training with low carbohydrates, do it on easy, low-intensity days to boost fat burning. Do NOT do this before or during high-intensity workouts or races, as it will likely hurt your speed and performance. Prioritize carbohydrates for your hard efforts.
ModerateQualifiesMEDIUM confidence
However, prolonged time spent in 'train low' may reduce ability to generate maximal power in high-intensity situations [12,19]. ... 'train low' may help improve an athlete's 'low gears' (maximizing fat oxidation) for prolonged exercise at lower intensities, but at the expense of losing the athlete's 'high gear' (maximal glucose oxidation) often needed during race situations.
Why this rating
Based on mixed study results and author clinical experience; some studies show no performance difference.
Source
Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations
Kenneth Vitale et al. · Nutrients · 2019
DOI 10.3390/nu11061289
narrative_reviewCited 259×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- For endurance events lasting longer than 2.5 hours, ingesting 60-70 g/h of carbohydrates (up to 90 g/h if tolerable) improves performance by maximizing exogenous carbohydrate oxidation rates.Good
- Following the thirst mechanism and drinking ad libidum (400-800 mL/h) is the recommended hydration strategy for endurance athletes to avoid exercise-associated hyponatremia (EAH).Good
Related findings · Macro partitioning
- Total daily protein intake of 1.6 g/kg/day is sufficient for maximizing resistance training-induced muscle gains, with an upper confidence interval of 2.2 g/kg/day.Strong
- Resistance exercise training combined with sufficient dietary protein intake acts synergistically to maximize skeletal muscle hypertrophy, with protein intake saturating around 1.6 g/kg/day for general populations and potentially requiring 2.0-2.2 g/kg/day for resistance-trained individuals.Strong
- Trans fats should be completely eliminated from the diet, as they increase LDL cholesterol, decrease HDL cholesterol, and are directly associated with increased coronary risk.Strong
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