In 2017, I was asked “does the ketogenic diet work?” In 2018, I was asked “does intermittent fasting work?” Well, the science shows that both can help people lose weight. In fact, a lot of my patients have found success with both keto and intermittent fasting.
But, the question to ask before starting any type of “diet” is: Is this something you can maintain? And, even more important, is it healthy for you in the longterm?
Intermittent fasting checks both of those boxes for most people. It’s easy enough to follow and can produce great results without compromising your health.
What does the science say?
A recent study from a team out of Australia compared intermittent fasting with and without calorie restriction to calorie restriction alone. They found 88 overweight women and randomly assigned them into three different groups: IF70, IF100, DR70, and DR 100.
The IF70 group consumed 70 percent of their recommended caloric intake (for weight maintenance) over a 7 day period. On non-consecutive days, they ate a breakfast that was about 32 percent of their recommended daily caloric intake and then would fast for 24 hours. On non-fasting days, they would eat 100 percent of their daily recommended caloric intake for weight maintenance. If you average the 32 percent caloric intake for 3 days along with 100 percent caloric intake for 4 days, you will find that the average is around 70 percent, which is why this group was labeled IF70.
The IF100 group consumed 100 percent of their recommended caloric intake over the course of 7 days. This was split up similarly to the IF70 group. On non-consecutive days, they ate a breakfast that was about 37 percent of their recommended daily caloric intake and then would fast for 24 hours. On non-fasting days, they would eat 145 percent of their daily recommended caloric intake for weight maintenance. If you average the 37 percent caloric intake for 3 days along with 145 percent caloric intake for 4 days, you will find that the average is close to 100 percent, which is why this group was labeled IF100.
DR70 & DR100:
For the DR70 group, each day they would consume around 70 percent of the recommended caloric intake for weight maintenance. This is basically what we call “cutting calories.” Whereas, in the DR100, or control, group, each day they would consume 100 percent of the recommended caloric intake for weight maintenance. According to the study, “daily energy requirements were calculated by averaging predicted daily energy expenditure from two published equations, both of which use age, gender, height, and weight variables.”
The women in IF70 group had the greatest reduction in weight and fat mass and improvements in total and LDL cholesterol as well as a reduced concentration of nonesterified fatty-acids when compared to the other groups. In other words, intermittent fasting paired with a reduction of caloric intake at 70 percent of daily energy requirements (as explained above) produced better results that dieting alone or intermittent fasting without cutting calories.
This study was a little difficult to sift through and understand at first. When broken down, the big picture is that you will likely lose more weight and improve your cholesterol levels without jeopardizing your insulin sensitivity with intermittent fasting PLUS cutting caloric intake rather than dieting alone or intermittent fasting without a reduction in caloric intake.
Let’s try an example of this. First of all, calculate your total daily energy expenditure (TDEE). I found a great calculator here. Enter in your age, sex, height, BMI, average activity level, and BMI. This will show you how many calories you should eat daily for weight maintenance.
My calculated TDEE was around 2,800 calories per day, which means I would need to consume 2800 calories a day on non-fasting days (4 days each week). On fasting days, I could eat around a 900 calorie breakfast and then fast for the following 24 hours. Wow, that’s a pretty big breakfast! On fasting days, you can still have “water, small amounts of energy‐free foods (e.g., “diet” drinks, chewing gum/mints), black coffee, and/or tea and 250 mL of very‐low‐energy broth (20 kcal/250 mL, 2.0 g protein, 0.1 g fat, 3.0 g carbohydrate) for lunch or dinner.” Again, not so bad, right?
Perhaps I’ll be giving this a try to shed off some winter/holiday weight.
What about you?
Do you think this would work for you? If you decide to give it a try, let us know how it goes.
Jeremiah Robinson is a licensed and certified Physician Assistant at T. Douglas Gurley MD in Atlanta, GA.