medwireNews: Reducing calorie intake to a quarter of normal needs for 2 days per week is as effective as smaller daily reductions in patients with type 2 diabetes, although care with either approach is needed for those with a history of hypoglycemia, shows a randomized trial.
The two approaches were statistically equivalent for change in glycated hemoglobin (HbA1c), report Peter Clifton (University of South Australia, Adelaide) and co-researchers.
The 51 patients who completed 12 months of intermittent energy restriction (500–600 kcal on 2 nonconsecutive days/week) had a significant 0.3% absolute reduction in HbA1c levels, compared with a 0.5% reduction in the 46 patients who completed 12 months of a 1200 to 1500 kcal/day diet. The 0.2% difference between the groups was within the prespecified equivalence margin of 0.5%.
The researchers suggest that the slightly poorer results in the intermittent dieting group may be because they were allowed to eat what they liked for the other 5 days of the week, with “no specific emphasis on improved dietary choices as were provided to those in the continuous energy restriction group.”
At baseline, the 70 and 67 patients randomly assigned to the intermittent and continuous calorie restriction groups, respectively, had relatively well-controlled diabetes, with corresponding average HbA1c levels of 7.2% and 7.5%.
This limited the chances of the interventions producing a large change in HbA1c, say the researchers, because baseline HbA1c was the factor most strongly associated with change during follow-up. Participants with a baseline HbA1c greater than 8% had the largest average reduction, of 1.4%, compared with just 0.03% among those with a starting level below 6%.
The participants were aged an average of 61 years and around 60% were taking antidiabetic medications, most commonly metformin, although 22% were taking a sulfonylurea and 20% using insulin.
A total of eight patients experienced hypoglycemia, but the average event rate did not significantly differ between the groups, at 2.5 and 2.0 with intermittent and continuous dieting, respectively.
The researchers note that all patients with hypoglycemic events had either had them previously or were not sure if they had. “For patients using sulfonylureas and/or insulin, regular monitoring is paramount,” they say, stressing also that these patients need dose reductions on the intermittent dieting days.
The patients’ average BMI was 36 kg/m2 and average bodyweight was 100 and 102 kg in the intermittent and continuous calorie restriction groups, respectively. During the intervention period, bodyweight fell by a corresponding 6.8 and 5.0 kg. These reductions were not considered statistically equivalent, in that the intermittent dieting appeared slightly more effective for this outcome; however, the team notes that a trial to demonstrate superiority would require more than 300 participants.
“Anecdotally, participants in the intermittent energy restriction group reported that although they were not following the protocol consistently after 3 months, they found that they could use it effectively to prevent weight gain because the energy restriction involved only 2 days,” Clifton et al write in JAMA Network Open.
They add: “The continuous energy restriction group found weight loss maintenance more difficult because, if they were not following the diet on a daily basis, they would regain weight owing to increased energy intake.”
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