Breakfast, athletes have long been told, is the most important meal of the day. And lunch and dinner aren't far behind. But what about the before-bed snack?
A pair of new studies offer contrasting views on how you can boost your strength or endurance by either adding or subtracting evening calories, so that your muscles remain in a heightened state of adaptation while you sleep. While the effects are subtle, they illustrate an often-neglected fitness rule: Sometimes when you eat is almost as important as what you eat.
The first study, by researchers at Maastricht University in the Netherlands, involved drinking a protein shake every night before bed for 12 weeks while lifting weights three times a week. Half of the 44 young men in the study received the supplement, which contained 27.5 grams of protein and 15 grams of carbohydrate, while the other half received a placebo shake with no calories.
The results, which were published in June in the Journal of Nutrition, revealed significantly greater gains in strength and muscle size for the protein group.
That might seem unsurprising, given that protein is known to stimulate the body's anabolic (muscle-building) processes. But not all protein counts. If you eat more than 20 to 30 grams of protein at a time, the anabolic benefits max out. North Americans typically get plenty of protein, but they eat just 10 to 15 grams at breakfast and lunch followed by a massive – and half-wasted – dose of 60 grams at dinner. Spreading your protein intake out through the day, all the way to bedtime, offers greater muscle-building benefits.
Some research has shown that eating protein immediately after a workout is particularly effective. In this case, though, the protein shake was consumed about four hours after the subjects finished their workouts, and they still saw major benefits, says lead author Tim Snijders, who is now a postdoctoral researcher at McMaster University in Hamilton.
"The window of opportunity might be bigger than originally hypothesized," Snijders says.
While a bigger bedtime snack seems to boost strength, researchers at RMIT University in Australia are exploring the opposite possibility with regard to endurance.
In a study published in the Journal of Applied Physiology, they had cyclists complete a hard interval workout after dinner, between 7 and 8 p.m., and then go bed without eating anything. As a result, their bodies stayed in a carbohydrate-depleted state, which stimulates endurance-boosting adaptations, while they slept. The next morning, before eating anything, they completed another, easier training ride while still in a carbohydrate-depleted state.
This approach is a variation on a training tactic known as "train low, compete high." By completing some (but not all) of your training in a low-carbohydrate state, you train your body to be more efficient and burn more fat. Then when you compete with full fuel stores, you have an advantage.
The problem with the train-low approach is that it's very difficult to do a high-quality training session with low carbohydrate stores. The advantage of the new approach, according to lead author Stephen Lane, is that you do your hardest training in the evening with full carb stores. Then you're asleep for most of the low-carb time, and do an easy workout the next morning.
The initial study focused on cellular markers of adaptation, showing, for example, that the approach boosted fat burning during the morning ride, compared with when the riders consumed the same number of overall daily calories but saved some for before bed.
Whether the cellular changes ultimately translate to better performance on the bike remains to be seen, but Lane, an accomplished cyclist and coach, has already begun experimenting with the train-low approach on himself and his athletes.
"I find the protocol works well for time-poor athletes, where they can get home from work, have dinner, then do an [interval] session followed by an easy ride in morning," he says. "I think many athletes have probably been doing this incidentally for years."
If nothing else, he adds, the morning-after ride on an empty stomach has other, less tangible benefits: "I have a feeling it's not only the metabolic adaptation that results in improved performance, but also the ability to learn to push harder while in a state of low carbohydrate availability."
Ultimately, which (if any) bedtime strategy you choose will depend on your goals, but the overall message is that timing does matter.
And yes, that applies to breakfast too. When British researchers tested cycling performance at 5 p.m. in a recent study, those who skipped breakfast were 4.5 per cent slower, even if they ate a big lunch to compensate.