Low-carb diets, including the latest “keto diet,” can cause low energy, headaches and questionable safety, with one large recent study showing a 32 percent higher risk of premature death for low-carb dieters. So some people have turned to the more moderate carb cycling.
This strategy alters the amount of carbohydrates eaten to maximize sports performance, build muscle and lose fat and weight. Bodybuilders and elite athletes in sports where weight matters have used the approach for years. Only lately has it spread to the public, showing up in health and fitness publications and as a hashtag in more than 350,000 Instagram posts. Compared with low-carb dieting, the theory goes, carb cycling puts the body under less stress and allows more diet flexibility and the physiological perks of carbohydrate-rich foods, such as the benefits of fiber.
The system is still theoretical because it’s mostly based on research on the effects of low-carb diets or periods of high-carb consumption (“carb loading”), not on alternating the two. But here’s why some athletes believe adding higher-carb days could be beneficial.
Restricting calories slows the metabolism and affects hormone levels, increasing hunger and the prospect of weight regain. Carb loading can temporarily raise metabolism and increase leptin, a hormone that blunts hunger, which together could promote weight loss. Also, research shows, carbohydrate-rich foods boost athletic performance and recovery, and carbohydrates burned for energy spare protein, which then can be used for muscle growth rather than fuel. Thus, the thinking goes, higher-carb days once in a while can help even non-athletes prevent a metabolic slowdown, enhance the effectiveness of workouts, trim fat and build muscle. And lower-carb days the rest of the time can encourage the body to burn fat for fuel.
(A Harvard study of 811 overweight adults found no significant difference in weight loss after two years between participants assigned a lower-, medium- or higher-carb diet. So although low-carb diets help some people lose weight, higher-carb diets can work as well when calories are reduced.)
No research on carb cycling tells whether it’s effective, much less safe over the long term. And it’s not easy to implement. Carb cycling takes plenty of math, meal prepping and weighing, and even more patience and experimentation.
Anyone who wants to try carb cycling should talk to their doctor first and meet with a registered dietitian to ensure they meet their energy and nutrient needs — and to help with the mind-boggling calculations needed.
Some general guidelines
Calculate your energy needs to know how many calories to aim for each day. You can get a rough estimate by multiplyng your weight in pounds by 10 for weight loss, 12 to maintain your weight and 15 to gain weight. On higher-carb days, try to get about half of your calories from carbohydrates; on lower-carb days, about 25 percent. Aim to consume 1 gram of protein per pound of body weight, and make up the rest of your calories from fat. (Each gram of fat is nine calories, and each gram of protein or carbohydrates is four calories.) Your protein will be pretty consistent; it’s carbs that you’ll alter. Then adjust your fat amounts to get the calories you need. Low-carb days will be higher in fat, and higher-carb days will be lower in fat.
Start with four high-carb and three low-carb days a week. It’s usually best to have higher-carb days when you’re exercising, so you can benefit from the boost in energy, performance and recovery. But your exercise routine, body type and health conditions all affect how often you need carb-rich foods and how much. You’ll probably need to adjust your carb-cycling until you find something that works.
On a lower-carb day, you could start with a breakfast of scrambled eggs with cheddar cheese, mushrooms and asparagus. Lunch could be a salad topped with salmon and oil and vinegar dressing, and snacks might be celery with natural peanut butter or cottage cheese. Dinner could be cauliflower rice with a grilled chicken breast and sautéed snow peas.
On a higher-carb day, you might add a slice of whole-grain toast at breakfast, a scoop of quinoa at lunch and some brown rice to your dinner while reducing the oil used on your salad and during cooking. You still need to hit calorie goals to lose weight or build muscle, and you should focus on high-quality whole foods. Added sugars, such as soda and candy, and starches, such as white rice and white bread, aren’t nutritious. Choose nutrient-dense carbohydrates that are low on the glycemic index, such as sweet potatoes, oats, quinoa and beans.
And be careful not to overdo it on a higher-carb day. It’s not a “cheat day,” so don’t think you can hit an all-you-can-eat pasta bar.
The bottom line
Carb cycling might be easier to stick to long-term than a low-carb diet. It also might help people move beyond weight loss or training plateaus. Further, modest reductions in carbohydrate-rich foods, especially those high in refined carbohydrates, might promote fat loss for some people.
But we don’t know enough about carb-cycling to recommend it. We do know consistency is key to getting results, and choosing the right types of carbs in moderate amounts is linked to a lower risk of some types of cancer, heart disease and stroke. Rather than focusing on the grams or percentages of carbs, protein and fats, you could hone in on a variety of whole foods, such as vegetables, beans, fish, poultry, fruit, whole grains, nuts and seeds. The best diet is one that’s sustainable and doesn’t require endless calculations.