Calorie cycling is also known as intermittent fasting, alternate day fasting or every other day fasting, but whatever you call it the premise is the same.
Calorie cycling has gained popularity as a weight loss diet and even promoted for overall health.
Instead of eating the same number of calories per day, you break up your weekly estimated calories and vary the calorie amount per day. For example, if someone needs about 2,000 calories per day, which would be 14,000 calories per week, you would unequally divide 14,000 into 7 days. Some days would be more than 2,000 calories, some less.
The exact number of calories per day varies according to different programs, but the concept is the same. You eat more some days, and in between you eat less. Here’s a look at some research behind calorie cycling and if you should do it or if it’s just another fad diet.
How Calorie Cycling Works
Proponents of calorie cycling claim that cycling calories is more natural, and humans aren’t designed to eat the exact same calories every day. Constantly eating a low number of calories can slow metabolism and could cause a weight loss plateau.
Calorie cycling does not keep you in a chronic decreased calorie intake and therefore may not lower metabolic rate as much as traditional dieting. Some research also suggests calorie cycling could prolong longevity, similar to prolonged calorie restriction in animal studies.
Calorie Cycling and Weight loss
Does calorie cycling work for weight loss? A 2005 study from The American Journal of Clinical Nutrition studied calorie cycling in non-obese subjects for 22 days. In this study, subjects fasted every other day. Researchers found fat break down increased, and this calorie cycling did result in significant weight loss.
Hunger on the fasting days did not decrease throughout the 22 days, and researchers suggested adding some food intake these days could make calorie cycling more feasible for the long term. A 2009 study also had similar results; obese subjects lost weight with calorie cycling over 8 weeks.
Is it better for Heart health?
The 2009 study also measured heart health outcomes from following a calorie cycling diet for 8 weeks. Researchers found that obese subjects on a calorie cycling diet for 8 weeks had significantly lower blood LDL cholesterol, blood pressure, total cholesterol and triglycerides. HDL cholesterol did not go down which is beneficial because HDL cholesterol is the good cholesterol.
Other animal studies with calorie cycling have also shown positive effects on heart health. Some animal studies have shown calorie cycling may reduce risk of type 2 diabetes, but not all human studies have shown the same results. Also, some human studies have not found an effect on blood pressure from calorie cycling.
Some researchers question if the heart health effects from calorie cycling studies are a result of weight and fat loss, not necessarily anything specific to calorie cycling. Some studies also show men or women have different responses to heart health and calorie cycling diets.
Does Calorie Cycling Increase longevity?
Following a calorie restricted diet has been shown in research studies to prolong life span in animals. The calorie restriction is usually pretty severe, meaning it’s more than just eating a little less than the body needs. Therefore, calorie restriction in humans does not appear attractive because chances are you are going to feel hungry most of the time.
Calorie cycling is thought to offer similar advantages with increasing life span, and it is less restrictive than following a strict calorie restrictive diet. Mice studies looking at calorie cycling and longevity show that genotype and when the calorie cycling is introduced to the mice affect the outcome of increasing life span with calorie cycling. More research is needed for humans and calorie cycling.
Should you do it?
Research studies are ongoing about the effects of calorie cycling and the health effects on humans. Some calorie cycling results from animal studies are not the same with humans. Short term studies have shown calorie cycling can be successful for weight loss, but does it have an advantage over following other healthy diet patterns? Also, not all calorie cycling in human studies show a benefit in increased fat breakdown and increased fat use for fuel.
Various programs are available for following a calorie cycling pattern. Some programs eat more on the fasting days than others. It is not clear what calorie cycling pattern is best for weight loss or other health indicators.
Keep in mind: Just because you are calorie cycling does not mean you can eat whatever you want on your feast or normal days. Healthy choices with fresh, whole foods should still comprise the majority of your food intake. Also, as the 2005 study noted, hunger on fasting days may not get any easier. Is that something you are willing to go through?
Another thing to keep in mind is exercising on calorie cycling. On days you are fasting or on a lowered calorie intake, exercising may be difficult. If you want to start calorie cycling, remember it is always best to consult your physician or dietitian especially if you are on medication.
References used in this article