Calorie Restriction vs. Intermittent Fasting. Which is better for weight loss?

Have you ever wondered about all of the intermittent fasting posts on social media? Let’s dive into some literature about intermittent fasting vs. good old calorie restriction.

 It seems like everywhere you look, influencers are touting their substantial weight loss using intermittent fasting. If you haven’t heard of it, many people report fasting “intermittently” to shed some pounds. Some people report using a 12:12, 16:8, 14:8, or 23:1 schedule with the first number corresponding to the number of hours you are fasting, and the second number being the amount of hours you eat. So someone on a 16:8 schedule may fast 16 hours and have an 8 hour eating window like 12-8PM for example. Many people state they can eat “whatever foods they want within their calorie goals” in this window and still lose weight. It makes you wonder if it is the act of fasting, or simply having less time available to consume calories.


This research study looked at people who restricted calories with and without time-restricted eating. This study followed 139 patients for 5 months. Patients were encouraged to weigh foods and take photos for accurate calorie-tracking. 69 patients did time restricted eating with a caloric deficit while 70 did a caloric deficit alone. 

The results showed no significant difference in weight change, waist circumference change, or body fat mass. Both groups showed improved BP, lipids, and cardio-metabolic risk factors. This graph shows TRE vs general calorie restriction.


This might be good news!  A caloric deficit is necessary for weight loss, but the timing of meals may not be so important. If your goal is to lose weight and improve cardio-metabolic risk factors, you can probably just have your first meal of the day when you feel hungry!


Eva Shelton, M.D.

M.D. Harvard Medical School, Brigham and Women's Hospital

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