PHILADELPHIA – Intermittent fasting may help improve weight status and metabolic health, but it is very challenging to adhere to and is possibly associated with certain risks, a physician with expertise in obesity and nutrition said during a presentation.
Andrew D. Bowser/MDedge News
Dr. Fatima Cody Stanford
“I do not necessarily recommend intermittent fasting to my patients, but I do have a lot of patients that will come to me asking about intermittent fasting,” said Fatima Cody Stanford, MD, MPH, of Massachusetts General Hospital Weight Center and Harvard Medical School, both in Boston, at the annual meeting of the American College of Physicians.
Intermittent fasting, which can take several forms including partial-day fasting, every-other-day fasting, or fasting two days per week, has been associated with positive physiological effects in an increasing number of recent studies, Dr. Stanford said.
Those physiological effects, reported in animals or humans, have included a potentially increased lifespan, decreased mortality related to cancers or cardiovascular disease, an improved insulin sensitivity, and reduced oxidative stress and inflammation, she said.
Additionally, weight loss and improvement in other health indicators, including insulin resistance, have been demonstrated in some studies of intermittent fasting that included normal weight or overweight human subjects.
In one systematic review and meta-analysis, intermittent fasting was found to be comparable with continuous energy restriction in overweight and obese adults for short-term weight loss.
Compared with no treatment, intermittent energy restriction was associated with a 4.14-kg drop in weight (95% confidence interval, 6.30-1.99; P less than or equal to 0.001), according to that meta-analysis.
In patients with type 2 diabetes, 12 months of intermittent energy restriction resulted in glycemic control comparable with continuous energy restriction, according to results of a randomized, 137-patient, noninferiority trial.
On the flip side, intermittent fasting has been associated with possible health risks, including having “a deleterious impact on fertility” and “a negative impact on bone health,” according to Dr. Stanford.
“These are things that I bring up with my patients,” she told her audience.
Lean mass may also be in jeopardy in intermittent fasters, according to authors of one systematic review and meta-analysis of randomized controlled trials published in the International Journal of Obesity.
Those investigators found that lean mass was decreased in intermittent dieters as compared with continuous dieters in the 9 trials they included. The mean difference was –0.86 kg (95% CI, –1.62 to –0.10; P = 0.03).
Even if intermittent fasting is comparable with continuous energy restriction in weight loss, getting to that point may be more difficult because of increased hunger, at least according to researchers in one randomized 1-year trial, Dr. Sanford noted.
Subjective hunger scores were higher at 4.7 for intermittent fasters versus 3.6 for continuous restriction participants (P = 0.002), results of that trial showed.
“It’s very difficult for most of us to sustain this,” Dr. Stanford said.
Dr. Stanford reported no relevant disclosures.