Research

Energy balance

A four-week ketogenic diet (70% fat, 15% protein, 15% carbohydrates) significantly increases relative VO2max and lactate threshold in off-road cyclists, primarily through reductions in body mass and fat mass.

If you are an endurance cyclist, switching to a high-fat, low-carb diet for a month during your base training phase can significantly boost your aerobic capacity (VO2max) and lactate threshold, largely because you lose weight and your body becomes more efficient at burning fat. However, be prepared for a drop in your maximum sprint power and high-intensity efforts, as your body will have less glycogen for those explosive moves. This is a trade-off: better endurance efficiency for less top-end speed.

ModerateSupportsMEDIUM confidence
Important findings of the present study include a significant increase in the relative values of maximal oxygen uptake (VO2max) and oxygen uptake at lactate threshold (VO2 LT) after the ketogenic diet, which can be explained by reductions in body mass and fat mass and/or the greater oxygen uptake necessary to obtain the same energy yield as on a mixed diet, due to increased fat oxidation or by enhanced sympathetic activation.
Adam Zając et al. · Nutrients · 2014

Why this rating

Small sample size (n=8) and short duration (4 weeks), but rigorous crossover design.

Source

The Effects of a Ketogenic Diet on Exercise Metabolism and Physical Performance in Off-Road Cyclists

Adam Zając et al. · Nutrients · 2014

DOI 10.3390/nu6072493

crossover · n=8Cited 184×
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DOI resolved against Crossref · corpus check 2026-06-10

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