Fasting diets don't produce superior health benefits despite increasing in popularity, say US researchers.
A randomised clinical trial comparing the alternate-day fasting diet with daily calorie restriction - the longest of its kind to date - found comparable health benefits between the two weight loss interventions.
After one year, weight loss among the 100 obese participants on either type of diet was about the same.
The fasting diet involved eating 25 per cent of a person's calorie needs on fast days and 125 per cent on alternating 'feast' days.
Those on the fasting diet lost six per cent of body weight, while the participants on a restricted calorie diet - 75 per cent of a body's calorie needs every day - lost 5.3 per cent of their body weight.
The findings of the University of Illinois at Chicago study, published in journal JAMA Internal Medicine, also showed blood pressure, insulin resistance and total cholesterol levels were not significantly different between the two intervention groups.
"The alternate-day fasting diet was not superior to the daily calorie restriction diet with regard to adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease," the authors concluded.
While more research is needed, Australian dietitian Nicole Dynan is not surprised by the findings as intermittent fasting can been "difficult" to stick with especially for people who are exercising a lot.
But fasting can work for some people, she said.
"Overall we all eat too much food. Intermittent fasting is really just another approach to calorie restriction.
"It's the same with low-carb diets, it's not necessarily that your reducing the carbohydrate as as macro-nutrient but it's the fact you're reducing total calorie intake that makes the difference," said Ms Dynan, spokesperson for the Dietitians Association of Australia (DAA).
Weight loss is really about finding an approach that suits a person's lifestyle and preference.
"Getting nutrition support and tailored advice is probably the key thing for everybody," Ms Dynan said.
