Why is this important?
Intermittent fasting, defined as a period of fasting interspersed with days of free food consumption, has gained popularity as an alternative to calorie restriction. It would offer equivalent weight loss results and few studies have been powered to compare the insulin sensitivity of the two approaches. However, no study has so far conducted measurements of postprandial glycaemia, predictive of the evolution towards diabetes. This study makes it possible to appreciate the interest of a restricted approach compared to a simple caloric restriction on these different parameters.
Methodology
This open-label randomized controlled study included three sequential parallel groups of patients aged 35-75 years who were at high risk of developing type 2 diabetes (AUSDRISK score ≥12) with no weight fluctuations greater than 5%. during the 6 months preceding inclusion. They were randomized (2:2:1) between three groups: (1) the intermittent fasting group had to reduce their energy needs by 30% on fasting days over a 4-hour window (between 8 a.m. and noon), followed by a 20-hour fast for 3 non-consecutive days per week. On fasting days, both meals were provided with substitutes provided by the investigators to ensure adequate nutritional intake; (2) the calorie restriction group had to reduce their energy needs by 30% and received meal replacements. They were to consume an evening meal but had no specific instructions on meal times. The standard care group received a brochure with nutritional recommendations. The intervention phase lasted 6 months. A final follow-up was conducted at 12 months.
Principle results
In total, the study included 209 participants (57% women, 58 years old, 34.8 kg/m²). After 6 months, the improvement in the area under the curve (AUC) of postprandial glycaemia compared to inclusion was greater in the intermittent fasting group compared to the calorie restriction group (-10.10 vs -3.57 mg /dl/min, p=0.03), while the AUC of postprandial insulin was greater for the first than for the second. No difference was observed between the two groups for glycated hemoglobin (HbA1c), fasting blood glucose or insulin.
Weight loss (-7.38 (-8.11 to -6.64]and -6.98 kg [-7,77 à -6,20] in the fasting and calorie restriction groups vs -2.43 kg [-3,52 à -1,34] in the control group), the loss of fat mass (respectively -6.19 [-7,34 à -5,03] and -5.76 kg [-6,87 à -4,66] vs -2,48 [-4,12 à -0,83]) and reduction in waist circumference (respectively -6.80 [-8,13 à -5,48] and -6.44cm [-7,81 à -5,06] vs -1,91 [-3,84, 0,02]) were greater in the two intervention groups vs. the control group, with no difference between the two.
Adverse effects were generally mild and resolved during the trial: fatigue, dizziness, constipation, headache. Fatigue was observed more frequently in the intermittent fasting group than in the calorie restriction group.
