Vesna Jovanovic / EyeEm/Getty Images

This method of switching between low and high carb diets is popular among some athletes, but is it a good way to lose weight? Our nutritionist finds out for herself.

Carolyn Williams, PhD, RD
February 06, 2018

Varying carb intake, or carb cycling, is a way of eating that athletes and bodybuilders have long followed to enhance performance. This eating plan may sound a bit extreme, but it’s quickly catching on as way to lose weight without sacrificing your favorite carb-rich foods.

Carb cycling has now gone mainstream, but is it really a good way to lose weight? Better yet, is it healthy? To better understand and evaluate carb cycling from a nutrition perspective, I followed a cycling plan for two weeks. Below, find everything you need to know about carb cycling, so you can decide if this eating plan is right for you.

RELATED: 5 Easy Ways to be Carb-Conscious

What is Carb Cycling?

Carb cycling is an eating approach where carbohydrate consumption varies between low and high intakes. This can be done either on a daily, weekly or monthly basis, but alternating every other day (or every two days for for some plans) seems to be the most popular format.

An example of a carb cycling plan would be eating a “low-carb” diet on Monday, Wednesday and Friday and eating a higher carb diet on Tuesday and Thursday. Keep in mind that “high-carb” doesn’t necessarily mean nothing but pasta and bread. Think of it as essentially a healthier version of how you normally eat.

While athletes have followed forms of carb cycling for years, the trend has quickly become a way for carb lovers to lose weight (while having energy and eating the foods they love periodically during the week). It’s also a popular eating strategy among intermittent fasting devotees as a way to stimulate weight loss and health outcomes.

Eat Well. Lose Weight. Healthy eating starts here, with the Cooking Light Diet.

How Does Carb Cycling Work?

Because there is no scientific or precise definition for “carb cycling,” plans vary by the individual. However, there seems to be some general consistencies. Most plans set a daily calorie goal that stays constant. Carb limits vary depending on the day.

A “low-carb” day means consuming 50g or less of carbohydrates. On these days, protein and fat intakes increase to help you meet your calorie needs. Recommended foods to eat on low-carb days are non-starchy vegetables (low-carb, low-cal veggies such as leafy greens, cauliflower, eggplant, and mushrooms), lean proteins, some nuts and nut butters, healthy fats, and then even more non-starchy vegetables.

A higher carb day is defined by most as consuming approximately 50% of your total calories from carbohydrates. Your macronutrients, or grams of carbs, protein and fat you need to eat within your calorie goal usually fall within the USDA’s Dietary Guidelines recommendations.

Foods on these days are generally the same as a low-carb day, but also include fruit, beans, starchy vegetables (higher carb vegetable such as potatoes, butternut squash, legumes, and corn), and some whole grains. Most plans recommend eating only gluten-free grains and avoiding dairy (however, with little scientific-backed explanation), avoiding highly processed foods and added sugars, and limiting alcohol intake.

Finally, carbohydrate intake is usually coordinated with exercise. Typically, higher-intensity workouts and cardio are encouraged on low-carb days. The theory is, eating fewer carbs triggers the body to tap into fat stores for energy, therefore enhancing fat loss.

Strength training is encouraged on higher carb days to provide muscles adequate energy for to repair and build lean body mass.

Is Carb Cycling Actually Healthy?

When I began evaluating carb cycling, I immediately reached a roadblock. There’s essentially no research on the health effects and weight loss potential of varying carbohydrates on a daily basis. While there’s plenty of data on following low-carb diets, as well as higher carb, lower fat diets, for a certain period of time, you won’t find much about alternating between the two every other day.

To effectively evaluate carb cycling from a nutrition perspective, I followed a cycling plan for two weeks. Based on my estimated energy needs, this is what my eating plan for one week looked like:

 Calories Per DayCarbs Per DayExercise
Monday & Wednesday1500 or less50g or less (~13% total cal)Cardio, HIIT workouts, sprints
Tuesday & Thursday1500 or less180g or less (~50% total cal)Strength training
Friday & Sunday1125 or less140g or less (~50% total cal) and 25% less calories Rest day
Saturday1500 or lessCheat day: Eat any foods that fit calorie and macronutrient needs. Aim for calories & 180g  or less carbs (~50% total cal)Strength training, cardio

After following this plan for two weeks, I analyzed my nutrient intake and compared it to my previous diet.

Surprisingly, my average daily intake of Vitamin A, Vitamin C, fiber, and potassium was around the same as before. On some days, it was even a little higher. My overall sodium intake decreased slightly, likely due to avoiding processed foods and following a diet rich in whole foods and vegetables.

Here’s what troubles me. For two weeks, my calorie intake averaged out to 1140 calories per day. This is less than what I typically need, and significantly less on days that I exercise.

My lowest calorie days—1125 calories or less—were also my low-carb days. On my higher carb days, I found it difficult to consume 1500 calories, even after increasing calories from fat significantly and eating more protein.

My calcium intake was less than 50% of my recommended daily needs, and my iron intake was inadequate on some days. I had a 2 ½ lb decrease on the scale (which could largely be water weight), but my clothes seemed to fit a tad better and I felt a little leaner.

JGI/Jamie Grill/Getty Images

So, Does Carb Cycling Really Work?

Without having any formal research to look at, the best we can do is glean information from testimonials. And while many seem positive, testimonials alone aren’t enough for health professionals to recommend carb cycling as an eating plan.

From a research perspective, we know relatively little about how carb cycling compares to other weight loss and performance-based eating protocols.

However, promising research does exist on individual components used in carb cycling. Studies suggest that increasing carbohydrate intake in coordination with workouts can potentially benefit athletes and very active individuals. Also, a 2015 meta-analysis suggests that low-carb eating plans are as effective, and maybe even more so for certain individuals, than a higher carb, lower fat eating plan. In fact, some studies suggest that low-carb eating plans may improve insulin sensitivity and reduce risk of cancer, heart disease and brain disorders.

For healthy individuals, following a carb cycling program is probably safe. With no exact definition for carb cycling, there’s no exact right or wrong way to follow the trend. If you try it, simply adjust the plan to fit your individual needs and ensure that you’re meeting your energy needs with nutrient-dense foods (not just steak and bacon). Listen to your body during exercise—and if you’re feeling fatigued, adjust your workouts as needed.