The Skinny on Carbohydrates.
Diet advice is a dime a dozen, which often makes it difficult to know what’s right, what’s wrong, what works, and what doesn’t. With respect to carbohydrates in the diet, “expert” recommendations vary from “eat as little as possible” to “make 65-70% of your calories carbohydrate foods”. With a range of recommendations that varied, how can we really assess the best carb guidance for ourselves?
Here are a few rules of thumb:
Not all carbs are created equal: Seek out nutrient dense carbs, foods that are rich in fiber, vitamins, and minerals. Fruits, whole grains, some starchy vegetables are good examples. Non-nutrient dense carbs like candy and soda pop, which contain sugar (a carbohydrate) but not much additional nutrition, should of course be eaten sparingly.
First and foremost, carbs provide energy. Many carbs contain vitamins and minerals (as mentioned above), but their first role in the body is energy provision to keep the brain, muscles, and other organs functioning properly. If you’re sitting on the couch all day and don’t require much energy, you don’t need as much carb. If you’re performing physical activity, however, your need for carbs increases. So a viable way to think of daily carb needs is, “You burn it- -you earn it.” On a day when you’re going to be particularly active, save a bit more room on your plate for carb-containing foods. On a not-so-active day, put fewer carbs on the plate. Athletes in-season need more carbs. In the off season, or when sidelined by injury, their carb needs may be adjusted down accordingly.
Dietary fat also provides energy, so why not adhere to a high fat, ketosis-style diet, and keep the carbs off the plate? While somewhat controversial, most health experts will tell you your diet should contain at least 40-50% calories from carbs, if not more. When carbs aren’t present and reliance on fat for energy increases, one tends to develop ketosis, a condition often marked by lethargy, fatigue, and mental confusion. A combination of carbs and fat in the diet allows the body to function more efficiently, as well as to preserve muscle protein.
But will carbs make me fat? Too much of any calorie-containing food may lead to weight gain. Carbs in particular have been called out lately, largely because of the weight loss success some people experience when cutting carbs from the diet. While it’s true that carb cutting may lead to rapid, sometimes significant weight loss it must be remembered that much of this initial loss is water loss. For every gram of carb you store, you store a near equal amount of water. Cut the carbs, you lose the water; your weight goes down-transiently. This rapid weight loss is really “Fool’s Gold”. It’s water, not body fat you’re losing. For real, sustained weight loss a prudent diet with moderate amount of carb, fat, protein is best.
Finally, recent studies suggest that a muscle depleted of its carb via habitual exercise, a low carb diet, or both, may be more prone to injury and less responsive during exercise recovery than a muscle with adequate carb reserves. If you exercise, it’s important to maintain some level of carb in the diet to be able to exercise effectively, at a higher intensity, and to recovery properly to set yourself up for the next day’s activity. That said, other research suggests that too much sugar in the diet may increase inflammation and exacerbate soft tissue and joint pain. So, the right balance of carbs is essential. More high-quality carbs, less sugar is the best way to go.
Nutrition research continues to evolve, and our perspectives about what constitutes a healthy mix of nutrients in the diet has changed over the years as well. Based on the best available evidence, a varied diet that contains a healthy mix of carbs (~55% of kcals), fats (~30% of kcals), and proteins (~15% of kcals) is best to avoid injury, maintain health, and be able to perform physical activity longer and harder. Of course this advise will require individualization for each person’s specific needs.
Mitch Kanter, PhD has served as Director of Health & Nutrition for Cargill and General Mills, and as Director of the Gatorade Sports Science Institute. He currently serves as Chief Science Officer for the Global Diary Platform, and as an Adjunct Associate Professor at the University of Minnesota.