Over the past few years, time-restricted feeding, a variant of intermittent fasting, has been touted as one of those amazing “magical” diets. The internet blurbs and even some national speakers told us, “Just don’t eat till about 9 or 10 am and stop eating 8 hours later and you will take care of your insulin resistance, your diabetes your blood pressure and your weight.” Well, like all fads, including pet rocks, the South Beach Diet, keto and now time-restricted feeding the truth is out there. The magic is in calorie reduction… no matter how you get it…
A recent study published in the New England Journal of Medicine, dated April 22, 2022, studied 139 patients with obesity with time-restricted eating (eating only between 8:00 a.m. and 4:00 p.m.) with calorie restriction or daily calorie restriction alone. For 12 months, all the participants were instructed to follow a similar calorie-restricted diet that consisted of 1500 to 1800 kcal per day for men and 1200 to 1500 kcal per day for women. What they found was that among patients with obesity, a regimen of time-restricted eating was not more beneficial with regard to reduction in body weight, body fat, or metabolic risk factors than daily calorie restriction.
Of the 139 patients who started the study, 135 participants (97.1%) completed 6-months of the study and 118 (84.9%) completed the 12-month study. For 12-months, the average percentage of the days participants adhered to both the prescribed calories and eating period was 84.0±16.1% in the time-restricted–eating group and 83.8±12.6% in the daily-calorie-restriction group. The mean weight change from baseline to 12 months was −17.6 lbs. in the time-restricted–eating group and -13.9 lbs. in the daily-calorie-restriction group. There was no statistically significant difference between the two groups in weight change.
Both time-restricted eating and daily calorie restriction were associated with reduced systolic and diastolic blood pressure over 12 months, with no substantial difference between the groups glucose levels, 2-hour postprandial glucose levels, scores on the insulin disposition index and HOMA–IR, and lipid levels were similar in the two groups during the 12 months also.
At the end of the day, time-restricted feeding is no better or no worse than standard dieting an in my practice, seems to be harder to do and harder to keep up in my patients.
NEJM April 22, 2022