LIVERPOOL — A small, new study on intermittent fasting, as in the 5:2 diet, showed that this approach reduced triglyceride levels by 40% after meals, compared with a conventional, daily calorie-restricted diet in healthy but overweight/obese individuals.

Presenting her work here at the Diabetes UK Professional Conference (DUPC) 2019, Rona Antoni, PhD, from the University of Surrey, United Kingdom, who is also a practicing dietitian, said: "Following a 5% weight loss, the intermittent fasting [5:2] diet, but not continuous energy restriction, led to significant improvements in postprandial triglyceride responses."

"If you do this repeatedly, then this could potentially be beneficial in people with raised triglycerides," she explained, highlighting that this is the first time such an effect has been observed in humans.

"The obvious question here is why did metabolic responses [in the intermittent fasting group] differ to the continuous energy restriction group? This is still under investigation, but it is perhaps unsurprising that a dietary approach that involves frequent periods of fasting may make the body more efficient at metabolizing/clearing fat from a meal," she remarked.

Comparing Metabolism Between Different Diets but With Equal Weight Loss

In her study, Antoni examined the chronic effects of intermittent energy restriction (fasting on a 5:2 diet with 630 kcal/day, for 2 days, and healthy eating for 5 days) compared to modest daily dietary restriction (600 kcal below daily requirements) in a total of 27 healthy, overweight/obese (BMI: 30.1 ± 1.0 kg/m2) participants.

This study required all participants to achieve a 5% weight loss, and to undergo postprandial assessments of glucose and lipid metabolism before and after attaining this goal.

This was necessary, explained Antoni, because "unequal weight loss between groups would have confounded metabolic comparisons," and she noted that this approach differs to that of most other weight-loss studies.

The main emphasis of the study was on postprandial metabolism, considering that most prior studies have looked at metabolism in the fasting state, she explained.

"We spend three quarters of our day in a postprandial fed state, and impairment in postprandial glucose and lipid metabolism are independent risk factors for cardiovascular disease," remarked Antoni.

In this real-world setting, "We wanted to find out if intermittent energy restriction offers any distinct metabolic advantages over and above its effects on body weight."

Also assessed were changes in body composition and time taken to achieve the 5% weight-loss goal.

Intermittent Fasting Led to Quicker Weight Loss

Antoni noted it took the intermittent fasting group [5:2 diet] less time to reach the 5% weight loss endpoint — a median of 59 days — than those on a modest daily calorie restriction, who took a median of 73 days to achieve the same goal.

"There were comparable improvements in adiposity and waist/hip circumference, and no differences were seen in fasting glucose or lipid profiles," she said.

The key finding from the study was that metabolic differences between weight loss via these two diets only became apparent in the postprandial period, she stressed,

A 5% weight-loss via the intermittent (5:2) diet led to a significant reduction in postprandial triglycerides, but this was not seen in the other group.

"The frequent bouts of fasting may offer very distinct metabolic advantages when compared to continuous dieting approaches," Antoni said.

"This shows that the intermittent diet is better at reducing postprandial triglycerides and highlights potential applications, especially in people who already possess elevated fasting (or nonfasting) triglycerides."

And from a dieter’s perspective, "The main appeal of this type of intermittent energy restriction…is that they need not 'energy restrict' every day," she concluded.

Asked to comment for Medscape Medical News, session comoderator Ian Davies, PhD, a nutritional scientist from Liverpool John Moores University with a particular research interest in cardiovascular disease, said: "I would speculate from the data shown that lowering the triglycerides, postprandially, will [in turn] show beneficial effects on the LDL."

This is likely to be via an impact on the size of LDL particles, leading to "larger, more buoyant particles, which…are less atherogenic than the small, dense," ones, he explained to Medscape.

Diabetes UK Professional Conference (DUPC) 2019: Talk entitled Intermittent fasting: weight loss and beyond. Presented March 7, 2019.

LighterLife supported the research. Antoni is a freelance dietitian for www.Citydieticians.co.uk. Davies has disclosed no relevant financial relationships.