Carbs and training performance: timing and amounts

Carbs and training performance go together: your muscles store carbohydrates as glycogen, and that glycogen is the fuel for intense training. As a rule of thumb, an athlete training an hour a day needs roughly 5 to 7 grams of carbs per kilo of body weight. At 75 kilos that is 375 to 525 grams a day.

In our experience many recreational lifters focus too much on protein and underrate carbs. Without a full glycogen store your last set falls apart, no matter how much protein you eat.

Why do carbs matter for your performance?

Carbs deliver the fastest fuel for your muscles. Your body breaks them down into glucose and stores the surplus as glycogen in muscle and liver. During intense or longer efforts you drain that store, after which your pace and strength can drop. Enough carbs can therefore support your recovery and your next session.

Trained muscle holds about 400 grams of glycogen, with another 100 grams or so in the liver. That is roughly enough for 90 minutes of hard effort. If you empty out halfway through a heavy session, a low glycogen store is a likely suspect.

For the full picture of nutrition around strength and recovery, read our plan for nutrition and muscle growth.

How many carbs per day do you need as an athlete?

It depends on how hard and how long you train. In quiet weeks 3 to 5 grams per kilo of body weight a day is often enough. Train hard for an hour and 5 to 7 grams makes more sense. With double sessions or workouts over two hours, 6 to 10 grams per kilo can fit.

These ranges line up with what the Voedingscentrum reports for athletes. In 2026 the Dutch Gezondheidsraad dropped its fixed minimum of 40 energy percent from carbs and put the emphasis on quality over an exact number.

Protein and fat do not disappear here. Treat these grams as your energy base, on top of which you keep eating protein for recovery and enough fat for your hormones.

Spread your carbs across the day instead of loading them into one meal. That keeps your energy steadier and tops up your glycogen store gradually. A 75-kilo lifter training five times a week often sits around 400 to 500 grams a day.

When is the best time to eat carbs around training?

Timing matters most around heavy sessions. Eat a carb-rich meal 1 to 3 hours before training, so your stomach is settled and your store is full. If the effort lasts longer than 60 to 90 minutes, 30 to 60 grams of carbs per hour can keep your pace up. Afterwards, carbs together with protein support your recovery.

Think oats with banana before, some sports drink or dates during, and rice with chicken after. For your pre-workout, caffeine plays a role too: together with carbs it can lower your sense of effort. Read more in our piece on caffeine and pre-workout.

On a quiet training day the exact timing matters less than your daily total.

What do carbs do to your blood sugar and triglycerides?

Carbs steer both your blood sugar and your triglycerides. After a meal your glucose rises, after which insulin moves it into your cells. A pattern with lots of fast sugars and little fibre can raise your triglycerides. Your fasting glucose responds to your total carb intake and to its quality.

In athletes these values can look different than in non-athletes, partly due to training and timing. Research suggests the quality of your carbs often matters more here than the sheer amount.

Fibre plays a part here. It slows the uptake of glucose, which can flatten spikes. Vegetables, fruit and wholegrain products deliver fibre without cutting back on your carbs.

Curious what training on an empty stomach does to your blood sugar and fat burning? Read our article on fasted training and your blood values.

Fast vs slow carbs: does it matter?

It matters, but mostly through timing. Fast carbs with a high glycaemic index give a quick glucose spike, handy around and during intense effort. Slow carbs with plenty of fibre give a steadier curve, nice on rest days and at regular meals. For your daily base, wholegrain products, vegetables, legumes and fruit can be a good choice.

Fast sources are things like sports drink, white rice and a ripe banana. Slow sources are oats, wholegrain pasta and lentils. Around training you go faster, the rest of the day mostly slower and higher in fibre.

A practical approach is to periodise: more carbs on heavy days, fewer on rest days. That matches your fuel to what your body actually asks of it that day.

My advice: work out your carb need with the table above first, then adjust it per training day. If you want to see where your triglycerides and fasting glucose stand, a 360 health blood test gives you a starting point. Discuss your results with your GP afterwards, and check with your sports doctor or dietitian if in doubt.

References

1. Voedingscentrum. Carbohydrates. 2024.
2. Gezondheidsraad. Dietary reference values for fats, carbohydrates and fibre. 2026.
3. Kerksick CM, et al. International Society of Sports Nutrition position stand: nutrient timing. Journal of the International Society of Sports Nutrition. 2017. PMID 28919842.

Disclaimer

Every blood test result includes a professional assessment by a BIG-registered doctor. This article gives general information and is not a substitute for medical advice. A blood test is a tool to walk into the conversation with your GP better informed, not a diagnosis in itself. For treatment decisions, discuss your results with your GP.