Between 4 and 24 hours after a hard workout, your muscles keep rebuilding their first energy store no matter how many carbs you eat, but the bigger energy store only grows if you eat lots of carbs.

After a hard workout, your muscles keep making the big energy store only if you eat a lot of carbs — if you eat few carbs, that big store doesn’t grow at all over two days.

Right after a super-hard workout, eating lots of carbs makes your muscles start rebuilding their first energy store (proglycogen) three times faster than if you eat fewer carbs.

After a really hard workout, eating a lot of carbs helps your muscles rebuild a special type of stored energy (macroglycogen) much better than eating fewer carbs.

Right after a super-hard workout, only about 1 in 8 of your muscle’s energy stores is in the big storage form — but if you eat lots of carbs afterward, that big store grows to nearly half of all your muscle energy.

If untrained guys eat a high-fat diet for 7 weeks, their muscles use less stored sugar during medium-intensity exercise compared to eating a high-carb diet — it’s like saving their fuel — but their legs still take up the same amount of glucose from the blood.