Do patients with type 2 diabetes still need to eat snacks?

The size and frequency of meals are important elements of nutrition, with considerable effects on the human health. A hypocaloric diet is a key component in both prevention and treatment of type 2 diabetes and it is usually apportioned into three main meals and two or three snacks in between.

Eating snacks is often advocated as a means of controlling body weight and glycaemic control, but studies endorsing this practice are lacking. In fact, it has been demonstrated that snacking leads to weight gain1 and increased risk of type 2 diabetes.2, 3 Snacking encourages higher energy intake by increasing food stimuli,4 hunger and the desire to eat,5 which is absolutely counterproductive to the treatment of type 2 diabetes.

On the other hand, diets incorporating intermittent fasting seem to be efficient for weight loss and type 2 diabetes risk reduction in overweight and obese populations.6 We have shown previously that breakfast and lunch consumption reduced body weight, hepatic fat content, fasting plasma glucose, C-peptide and glucagon, and increased insulin sensitivity more than a diet with the same caloric restriction divided into six more frequent meals7 in patients with type 2 diabetes. Also for glycaemic control it may be more beneficial to eat larger meals rich in fibre instead of dividing them into smaller portions.8

However, for a long-term effectiveness of any dietary approach not only metabolic benefits are important, but also the effects on quality of life and eating behaviour. To the best of our knowledge, no study has been published as yet on the effect of meal frequency on quality of life, depressive symptoms and eating behaviour in patients with type 2 diabetes.

In this secondary analysis of our previously published data, during a 24-week crossover trial, we studied quality of life, Beck depression score and eating behaviour in response to a hypocaloric diet consumed as either six (A6) or two meals, breakfast and lunch, per day (B2). The characteristics of the sample and the methods are described in detail elsewhere.7 Briefly, 54 patients with type 2 diabetes treated by oral hypoglycaemic agents (both men and women, aged 30–70 years, body mass index 27–50 kg/m2 and glycated haemoglobin 6–11.8%, that is, 42–105 mmol/mol) were randomized within a 24-week crossover single-centre study (conducted in Prague, the Czech Republic). After a 1-month run-in period, the participants began a 12-week regimen of either six (A6) or two (B2) meals a day. The A6 regimen consisted of three main meals (breakfast, lunch and dinner) and three smaller snacks in between. The B2 regimen consisted of breakfast (eaten between 0600 and 1000 hours) and lunch (eaten between 1200 and 1600 hours). Then the regimens were switched for subsequent 12 weeks. The study protocol was approved by the Institutional Ethics Committee.

The diet composition under both regimens followed the Study Group on Diabetes and Nutrition of the European Association for the Study of Diabetes guidelines, with the same caloric restriction of −500 kcal/day, based on the measurement of resting energy expenditure of each subject by indirect calorimetry (metabolic monitor VMAX; Sensor Medics, Anaheim, CA, USA). The diet derived 50–55% of total energy from carbohydrates, 20–25% protein, <30% fat (7% saturated fat, <200 mg/day of cholesterol), and 30–40 g/day of fibre. Participants were asked not to alter their exercise habits during the study.

Quality of life was assessed using two questionnaires: Obesity and Weight-Loss Quality of Life (OWLQoL) and Weight-Related Symptoms (WRSM)—see Supplementary Appendix 1 and 2.9 We used the Three- Factor Eating Questionnaire10 to monitor changes in eating behaviour and the Beck Depression Inventory to screen for depressive symptoms—see Supplementary Appendix 3.11 For statistical analysis we used a 2 × 2 crossover analysis of variance.

The variables of quality of life, Beck Depression Inventory and Three-Factor Eating Questionnaire are shown in Figure 1. Quality of life (the OWLQoL score) increased (P<0.01) comparably under both regimens (Figure 1a). The decrease in negative WRSM was borderline significant in A6 (P=0.05) and not statistically significant in B2 (P=0.06), with no significant difference between treatments (P=0.6; Figure 1b). Beck depression inventory score decreased (P<0.05) in response to both regimens, more with B2 (P=0.04; Figure 1c). Dietary restraint (Figure 1d) increased and disinhibition (Figure 1e) decreased comparably under both regimens (P<0.01 each). Feelings of hunger remained unchanged in A6 but decreased significantly in B2 (P<0.001; difference between treatments: P<0.001; Figure 1f). No substantial unfavourable effects of the regimens were observed.

Figure 1
figure1

Changes in quality of life, Beck Depression Inventory and Three-Factor Eating Questionnaire. Changes from baseline in response to the regimen of six (A6) and two meals a day (B2), means±95% confidence intervals. Significance of the factor treatment (assessed by 2 × 2 crossover analysis of variance) is indicated by *P<0.05, ***P<0.001 and NS for nonsignificant. (a) ΔOWLQoL, n=48; (b) Δ WRSM, n=48; (c) ΔBeck depression score, n=47; (d) Δdietary restraint, n=47, (e) Δdisinhibition, n=47; (f) Δhunger, n=47.

Both regimens elicited a positive effect on the quality of life, Beck score of depression and eating behaviour. The positive effects on depressive symptoms and feelings of hunger were greater with B2.

The mechanism by which B2 can reduce depressive symptoms may be change in concentrations of various neuromediators including increased production of brain-derived neurotrophic factor in response to intermittent fasting, which has been shown to increase the resistance of brain neurons to dysfunction and degeneration in animal models.12

The three-factor eating questionnaire revealed that dietary restraint increased under both regimens, suggesting better voluntary control over food intake, aimed at reducing body weight. The decrease in disinhibition in both regimens means that the participants were less likely to overeat in, for example, stressful situations. A greater decrease in reported feelings of hunger in B2 suggests easier adherence to the regimen of breakfast and lunch compared with A6, in the long term. Decreased hunger in response to lower meal frequency has already been demonstrated.5, 13 One probable explanation of this finding is that larger meals impart the sense of fullness and satiety and inhibit ghrelin,13 making periods of fasting more bearable than being hungry all the day long, from eating more smaller meals without getting full.

In conclusion, both regimens elicited a positive effect on the quality of life, Beck score of depression and eating behaviour. The positive effects on depressive symptoms and feelings of hunger were greater with B2. These results, together with the metabolic data (that is, greater positive effects of B2 on body weight, hepatic fat content, fasting plasma glucose and increased insulin sensitivity7) suggest that for long-term adherence of type 2 diabetic patients to a hypocaloric diet rich in fibre, eating large breakfasts and lunches may be more beneficial than the usual snacking model. Further larger-scale, long-term studies are essential before offering recommendations in terms of meal frequency.

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Acknowledgements

This work was supported by the project grant IGA MZCR NT/14250-3 from Ministry of Health, Prague, Czech Republic and Institutional Support MZCR 00023001 (IKEM, Prague, Czech Republic).

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Correspondence to H Kahleova.

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Supplementary Information accompanies this paper on European Journal of Clinical Nutrition website

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Kahleova, H., Belinova, L., Hill, M. et al. Do patients with type 2 diabetes still need to eat snacks?. Eur J Clin Nutr 69, 755–756 (2015). https://doi.org/10.1038/ejcn.2015.46

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