Matt Fitzgerald—If you’re like most people who pay attention to expert nutrition advice, you probably think that you should eat snacks. The concept of snacking has acquired healthful connotations lately. It is purported to raise the body’s metabolic rate, prevent weight gain, maintain steady blood glucose levels, prevent midmorning and mid-afternoon energy crashes, and, in athletes, enhance workout performance.
It may surprise you to learn that there is very little science to support these widely believed-in benefits of snacking. In fact, the research on snacking suggests that it has no effect on metabolic rate and is as likely to promote weight gain as prevent it. And the importance of snacking in relation to maintaining steady blood glucose levels and energy is much smaller than the importance of what you eat in regular meals and your exercise habits.
In short, there is no basis in evidence for the idea that everyone should eat snacks. The truth is that some people need daily snacks while others don’t, and that the quality of any snacks you do eat is more important than whether or not you snack at all.
Many nutrition experts recommend a “grazing” approach to diet, where one eats small meals and snacks frequently instead of large meals infrequently. This approach is believed to keep the body’s metabolism elevated, so that one burns more calories at rest throughout the day and is therefore less likely to gain weight. But a study at the University of Wisconsin-La Crosse compared the habitual daily eating frequency and basal metabolic rates of 22 women and found absolutely no connection between the two variables. In other words, your resting metabolic rate is likely to remain the same whether you eat twice a day or six times.
Meanwhile, studies looking at the relationship between snacking habits and body weight have yielded surprisingly varied results. A 2005 study by Swedish researchers found that obese men and women snacked more regularly than a reference population. But a 2010 study of American adolescents found that the heavier snackers tended to be leaner than those who ate fewer snacks.
Such contradictions disappear, however, when snacking on healthy foods (fruit, yogurt, etc.) is distinguished from snacking on unhealthy foods (chips, candy, etc.). Healthy snackers tend to be leaner than unhealthy snackers. But it’s not the snacking itself that matters—it’s the healthy food choices. People who eat healthy foods are leaner than average whether they snack or not.
Finally, relying on snacking to maintain steady blood glucose and energy levels is like relying on moonlight to see while driving at night. Sure, it helps a little, but it’s not the best tool for the job. Maintaining a regular exercise habit and eating healthy meals with a low glycemic index (i.e. not too many refined carbohydrates) have much more powerful effects on glucose and energy regulation than snacking does. For example, a number of studies have shown that working out attenuates the blood glucose response to the next meal eaten after the workout.
Put it this way: If you need snacks to avoid “crashing” in the middle of the morning and afternoon, there’s a good chance you’re either not exercising enough or you’re making poor food choices at mealtimes.
Does this mean that nobody should snack? Not at all. Snacking may be necessary to meet your daily energy needs during periods of heavy training. The number of calories your body burns each day can increase dramatically between periods of lower-volume maintenance-level training and periods of peak training before races. As your training load grows, you can supply some of the additional energy needs that come with it by increasing the size of your meals. But it may be impractical to meet all of your additional energy needs this way. If you are training smartly and eating healthy, balanced meals, and yet you find yourself hungry and/or lethargic between meals, you probably need to snack.
Your body is smart. Let it tell you what it needs!
5 Great Snacks for Endurance Athletes
1. Whole fruit: A healthy source of carbs
2. Vegetable sticks with light dipping sauce: Not getting enough veggies in meal? Get more in snacks!
3. Low-fat fruit yogurt: A perfect balance of carbs, fat, and protein
4. Beef, turkey or fish jerky: A lean protein source
5. Nuts (almonds, cashews, peanuts, etc.): A satisfying source or healthy fats and protein
Check out Matt’s book, Racing Weight Quick Start Guide: A 4-Week Weight-Loss Plan for Endurance Athletes.