If healthy young guys take L-carnitine and carbs for 12 weeks, they might burn 6% more energy during light workouts — mostly by burning more fat, not carbs.

If healthy young guys take a certain amount of L-carnitine with carbs every day for 12 weeks, they might store more carnitine in their muscles, burn more energy during light exercise, and avoid gaining fat compared to just taking carbs.

If healthy young guys take L-carnitine with carbs twice a day for 12 weeks, they don’t gain the extra body fat that usually comes from just taking carbs — even though both groups are eating more calories than they need.

Taking L-carnitine with carbs for 12 weeks might turn up the activity of 73 genes that help the body burn fuel better — especially those involved in how insulin works and how fats are used — in healthy young guys, compared to just taking carbs.

If young, healthy guys take sugar supplements for 5 days, their muscles store more energy, but taking creatine doesn’t do the same — so sugar seems to fill up muscle fuel better than creatine when not working out.

If young, healthy guys take 20 grams of creatine every day while eating a super high-carb diet after intense exercise, they rebuild their muscle fuel 82% faster in the first day compared to just eating high carbs alone.