What Should Athletes And The Rest Of Us Eat At Night?
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(Inside Science Currents Blog) -- Ingesting the right sources of energy and nutrients, at the right time and for the maximum benefit, is a big deal. So much so that even small questions can garner intense interest. A Google search for "what to eat before bed" turns up 41.5 million results, for example.
Eating a big bowl of ice cream right before bed probably isn't great for your health. But what about some low-fat cottage cheese? Is that good for you if you're trying to lose weight? What if you're a bodybuilder or distance runner? The research on what to eat at night and how late-night snacking affects the body is relatively underdeveloped, said Michael Ormsbee, an expert on human performance and nutrition at Florida State University in Tallahassee.
In May, at the annual meeting of the American College of Sports Medicine in San Diego, Ormsbee described some interesting experiments on this issue to a standing room only crowd. Eating at night is relevant for research related to obesity, muscle repair, and muscle building. It's possible that at least for some, eating soon before sleeping could reduce sleep quality or cause the body to store fat excessively. Eating right before bedtime could cause food to be processed and digested differently than it would be during the day.
Previous research showed that the levels of glucose and insulin in the blood responded differently to the same meal at different times of day. Additionally, people tend to feel less full from food eaten between 6 and 10 p.m., even if a similar meal earlier in the day would leave them feeling stuffed.
Ormsbee, along with colleagues, began investigating nighttime eating and a head-spinning number of related variables -- how changes in portion size can have different effects, whether food being part of dinner or a snack was important, whether people should wake up at night to eat, and whether exercise made a difference.
Ormsbee's team found that small portions of protein-rich beverages before bed appeared to increase metabolism and satiety (how full someone feels).
However, he's not sure if that's a good thing, especially if late-night snacking discourages people from eating breakfast the next morning. In an email to Inside Science after the conference, he wrote: "While this might be good in terms of lowering total energy intake for a day (because they are less hungry), we can’t be certain this is good. What if they overeat at lunch and dinner because they skipped breakfast?"
Some of Ormsbee's other experiments have similarly curious caveats. He identified that proteins from milk, specifically whey protein and casein, can have certain benefits when taken in late at night. But if these high-protein, late-night snacks are added to diets that are already very high in protein, they don't necessarily have the same effects.
Add exercise into the mix, and the situation becomes even more complicated. Specific types of bedtime snacks can cause beneficial changes to the way the body processes carbohydrates and its overall metabolic rate. Athletes may say they feel more recovered after the snacks. But no one has documented changes in actual athletic performance, Ormsbee said.
His talk at the meeting was paired with one from Luc van Loon, a professor of exercise science at Maastricht University in the Netherlands, who discussed his own experiments with protein ingested before and during sleep.
His research group looked specifically at how nighttime eating influences muscle, metabolism, and recovery. In one project, they followed carbon-based tracers from farm to the body. First they gave them to a cow, which incorporated them into its milk. That milk was collected and refined into a protein drink. After subjects ingested the drink, the researchers did muscle biopsies, which showed that the protein reached the muscles.
Then van Loon and his colleagues went one step further. They brought people to the lab and inserted tubes through their noses to their stomachs. While those subjects slept, the researchers pumped some the tracer-infused protein into their stomachs. Muscles biopsies in the morning showed that this protein had now been incorporated into the subjects' muscles. The results worked as a proof of concept to show that protein digestion works at night, and showed that the same proteins, ingested while sleeping, could help maintain muscle tissue in the body.
It's not clear exactly how this finding could be applied. It definitely doesn't demonstrate that the technique could or should be used with weekend warriors, bodybuilders, or elite athletes.
However after telling the room full of researchers that this was early research, van Loon told them something they probably expected. He was contacted by numerous coaches asking how to obtain the feeding tubes used in the experiment.