Fasting or Daily Calorie Restriction?
Should you fast or practice daily calorie restriction to lose more weight and improve your blood pressure, blood sugar, and cholesterol?
A study published in the Annals of Internal Medicine on April 1, 2025, found that participants who practiced intermittent fasting three non-consecutive days of the week lost more weight in 12 months than those who practiced daily calorie restriction. The fasting group lost on average 8% of their body weight, and those who practice daily calorie restriction lost 5% of their weight, with the fasting group losing on average 6.4 more pounds.
How the Study Was Conducted
The study included 165 overweight and obese individuals, with 84 participating in the fasting arm and 81 in daily calorie restriction. Their BMI or body mass index ranged from 27 to 46. Both groups were asked to get 300 minutes of moderate-intense exercise a week, which is twice the amount the U.S. exercise guidelines recommend. Both groups received a high-intensity behavioral program with support.
The intermittent fasting group followed a 4:3 fasting program. They fasted three non-consecutive days of the week and reduced their calories on those days by 80%. Thus, someone who normally consumes 2,000 calories a day would only consume 400 calories three days a week. They would eat a normal amount on the other four days of the week.
Therefore, the 4:3 fasting group reduced their total weekly calories by 34%. If we stick with 2,000 calories a day times 7 days, we have 14,000 calories for the week minus 1600 calories times the three fasting days, which represents a 34% weekly reduction in calories.
The group that engaged in daily calorie restriction reduced their daily calorie consumption to match a total reduction of 34% over the week, reducing some calories each day.
In the end, both groups reduced their weekly calorie intake to an equal percentage. Â Yet there were differences in the amount of weight lost between the groups.
Results
Of the fasting participants, 38% lost at least 10% of their body weight compared to 16% in the daily calorie restriction group. One hundred twenty-five completed the study, with 30% of those in the daily calorie restriction group dropping out (N=24) versus 19% of the 4:3 fasting group (N=16).
To me, this finding makes sense as it seems reducing calories each day would be harder to follow than a small consumption of calories three days a week. Â In other words, tracking calories daily seems harder than just tracking three days a week.
Those in the fasting group showed better improvements in blood pressure, blood sugar, and cholesterol than the daily calorie restriction group.
Also, the body will adjust its metabolic rate downward to a greater degree with daily calorie restriction, more so than with periodic restriction. We discussed this in Zig Zag Your Way to Easy Weight Loss.  You want to keep your body guessing by fluctuating your intake of calories daily, but creating a calorie deficit for the week.
