Obese people with high levels of abdominal fat (‘belly fat) face increased risks for development of chronic diseases, such as non-alcoholic fatty liver disease (NAFLD), cardiovascular disease and type II diabetes mellitus (T2DM). Within nutritional research we are interested in the prevention of disease. This requires an accurate estimation of the individual health status, to allow intervening with dietary and life style changes before the onset of disease.
Optimal health can be defined as the capacity of an organism to keep metabolic balance in an ever changing environment and especially in response to a wide range of stressors. The individual’s capacity to respond to dietary challenges is called ‘phenotypic flexibility’. Phenotypic flexibility can be a very important indicator of individual health status, as it might reflect the (dys)functioning of metabolic organs, such as liver, adipose tissue and gut.
The Belly Fat study
In the Belly Fat study both phenotypic flexibility as an important parameter of individual health as well as the ‘power of nutrition’ to prevent or reduce risk factors for disease were studied. The objective of the Belly Fat study was to compare the effects of a 12wk intervention with two energy restricted diets that differed in nutrient quality on metabolic health and phenotypic flexibility. The study was broadly implemented within the division of Human Nutrition as multiple chairs were involved.
The study was a parallel-designed randomized 12wk intervention study in which 111 participants with abdominal obesity (BMI >27 kg/m2 or waist circumference >88cm for females, >102cm for males) were randomized over three groups; a Western-type or Targeted 25%ER dietary advice group or control group. The Targeted diet aimed to improve metabolic health by including MUFA, n-3 PUFAs, soy protein and fiber. Before and after the intervention, participants were extensively phenotyped to study the potential additional effects of nutrient quality over weight loss on metabolic health. Measurements included modern imaging techniques to quantify abdominal body fat distribution and liver fat, vascular measurements, tissue and blood collection as well as computer-based tasks and questionnaires. Most importantly, we applied a mixed meal test high in fat, sugar and protein to gain insight in phenotypic flexibility. Blood and tissue samples were collected before and up to 6 hours after consumption of this mixed meal. In addition to measuring classic markers of metabolic health, state of the art ~omics techniques (metabolomics, transcriptomics) will be applied in the nearby future as sensitive readouts for the effects of our dietary interventions on metabolic health.
Execution of the study
This study was executed between October 2014 and April 2015, analyses are still ongoing.