'Diet quality still matters' with popular weight loss technique intermittent fasting

Key takeaways:

• Intermittent fasting may be more appealing to patients than typical calorie restriction.
• There are several limitations when it comes to who should partake in the technique.

BOSTON — Intermittent fasting is a popular weight loss technique, but there are a few considerations that physicians should keep in mind when discussing it with their patients, according to a presenter at the ACP Internal Medicine Meeting.

In her presentation, Michelle McMacken, MD, FACP, an associate professor of medicine at the NYU Grossman School of Medicine and executive director of nutrition and lifestyle medicine at NYC Health + Hospitals, polled the audience, asking which eating pattern had the most “buzz” around it. Although there was a lot of interest in the keto, DASH and plant-based diets, patients were most often asking about intermittent fasting.

The popular technique has previously shown benefits for weight loss, regardless of which variation patients use. However, McMacken said a key point to note “is that there is really no evidence that intermittent fasting is any better for weight loss than just traditional calorie restriction.”

“It just might be more palatable, no pun intended,” she said. “It might be more appealing to people than actually counting calories.”

This was demonstrated in a randomized controlled trial published in Annals of Internal Medicine, she said.

As Healio previously reported, the trial including 90 participants revealed that, compared with no intervention, both time-restricted eating and calorie restriction were more effective in reducing weight. There was no significant difference between the two approaches at 1 year; absolute weight loss compared with the control group was –4.61 kg (95% CI, –7.37 to –1.85) for the intermittent fasting group and –5.42 kg (95% CI, –9.13 to –1.71) for the calorie restriction group.

“Intermittent fasting generally just reduces people's calorie intake. It's just another way to reduce your calorie intake without necessarily having to count calories,” she said. “Diet quality still matters.”

Because patients do not have to count calories at all on this diet, it is “thought to be among the most promising in terms of adherence.”

“You just watch the clock, not the calories,” she said. “Of course, as with any diet, if you've lost weight and you want to keep it off, you’ve got to stay on some version of what you were doing to get there in order to maintain the weight loss.”

McMacken also discussed who should and should not partake in intermittent fasting.

“Don't recommend it if someone's pregnant, or if they're breastfeeding, if they're underweight, or if they have a history of an eating disorder,” she said. “Those are not great situations to recommend it.”

She also noted some issues with intermittent fasting that PCPs should pay attention to.

“There is a disproportionate loss of lean muscle mass and lean body mass that has been seen with intermittent fasting, so just something to keep an eye on,” McMacken said. “Make sure your patients are consuming adequate protein during their resistance training. And finally, a patient on hypoglycemic medication needs to be very careful, of course, that they're going long periods without eating and probably adjust their medications.”

References:

• Lin S, et al. Ann Intern Med. 2023;doi:10.7326/M23-0052.
• McMacken M. Dietary trends explained. Presented at: ACP Internal Medicine Meeting; April 18-20, 2024; Boston.