Pathways and mechanisms linking dietary components to cardiometabolic disease: thinking beyond calories

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Author(s): Stanhope KL, Goran MI, Bosy-Westphal A, King JC, Schmidt LA, Schwarz J-M, Stice E, Sylvetsky AC, Turnbaugh PJ, Bray GA, Gardner CD, Havel PJ, et al
Publication name: Obes Rev. 2018 May 14. doi: 10.1111/obr.12699. [Epub ahead of print]
Publication year: 2018

Abstract

Calories from any food have the potential to increase risk for obesity and cardiometabolic disease because all calories can directly contribute to positive energy balance and fat gain. However, various dietary components or patterns may promote obesity and cardiometabolic disease by additional mechanisms that are not mediated solely by caloric content. Researchers explored this topic at the 2017 CrossFit Foundation Academic Conference ‘Diet and Cardiometabolic Health – Beyond Calories’, and this paper summarizes the presentations and follow-up discussions. Regarding the health effects of dietary fat, sugar and non-nutritive sweeteners, it is concluded that food-specific saturated fatty acids and sugar-sweetened beverages promote cardiometabolic diseases by mechanisms that are additional to their contribution of calories to positive energy balance and that aspartame does not promote weight gain. The challenges involved in conducting and interpreting clinical nutritional research, which preclude more extensive conclusions, are detailed. Emerging research is presented exploring the possibility that responses to certain dietary components/patterns are influenced by the metabolic status, developmental period or genotype of the individual; by the responsiveness of brain regions associated with reward to food cues; or by the microbiome. More research regarding these potential ‘beyond calories’ mechanisms may lead to new strategies for attenuating the obesity crisis.

Summary

As concluded by the authors of the publication on the outcome of a discussion about ‘Diet and Cardiometabolic Health – Beyond Calories’ in the context of the 2017 CrossFit Foundation Academic Conference in San Francisco, California, randomized controlled trials (RCTs) consistently demonstrate that consumption of low calorie sweeteners may help to decrease calorie intake, particularly when used as part of comprehensive weight loss programmes. Furthermore, several studies that were not conducted as part of weight loss programmes also showed no effects of low calorie sweeteners to increase body weight, despite the fact that it has been suggested that low calorie sweeteners’ consumption may indirectly affect energy balance.

Discussing why some epidemiological studies have shown positive associations between low calorie sweeteners and obesity or type 2 diabetes (T2D), the authors note that these studies do not demonstrate causation and are limited by the possibility of residual confounding and reverse causality. Specifically, individuals with higher body mass index (BMI) who are concerned about their weight or patients with T2D may choose to consume low calorie instead of caloric sweeteners.

Regarding potential mechanisms that have been suggested based on rodent studies, a systematic review by Rogers et al (2016) reported that in 62 of 90 animal studies low calorie sweeteners did not increase body weight and, importantly, it has been questioned whether any of the suggested mechanisms occur in humans. On the contrary, RCTs indicate that substituting low calorie sweeteners for sugar resulted in a modest weight loss in adults. While most of the published studies have been conducted with the use of aspartame, it does not appear that any of the available RCTs using different low calorie sweeteners or combination of sweeteners revealed any adverse effects of their consumption on risk factors for obesity or cardiometabolic disease. Therefore, the authors note that low calorie sweeteners may be a useful tool for increasing adherence to behavioural weight loss regimens, and that more studies are needed to study the long-term effects of the individual low calorie sweeteners.

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