Lifestyle and Genetics in Obesity and type 2 Diabetes

Abstract

Obesity and type 2 diabetes mellitus are multifactorial health threats caused by a complex interplay between genetic predisposition and the environment with dramatically increasing worldwide prevalence. The role of heritability in their etiology is well recognized, however, the numerous attempts made in order certain genetic variants determining individual susceptibility to be identified have had limited success, until recently. At present the advancements in human genetics and the utilization of the genome-wide association approach have led to the identification of over 20 genetic loci associated with, respectively obesity and type 2 diabetes. Most of the genes identified to date, however, have modest effect on disease risk suggesting that both diseases are unlikely to develop without the individual being exposed to obesity- and/or type 2 diabetes-promoting environment. Indeed, unhealthy lifestyle, characterized by physical inactivity and food overconsumption is an unequivocally established risk factor for obesity and type 2 diabetes. Numerous epidemiological studies and randomized controlled trials, on the other hand, have demonstrated that lifestyle modification is effective in obesity and type 2 diabetes prevention. Furthermore, gene-lifestyle interaction studies suggest that genetic susceptibility to obesity and type 2 diabetes may be partially or totally kept under control by healthy lifestyle or lifestyle modification and that lifestyle determines whether an individual is likely to develop the disease. Inherited factors, however, seem to influence individual response to a lifestyle intervention program and even the motivation for lifestyle change. Personalized interventions according to genotype may be, therefore, considered in the future. By then lifestyle modification targeting dietary change and increased physical activity may be recommended for successful obesity and type 2 diabetes prevention irrespectively of genetic susceptibility.

Comparison of laparoscopic Roux-en-Y gastric bypass with laparoscopic sleeve gastrectomy for morbid obesity or type 2 diabetes mellitus: a meta-analysis of randomized controlled trials

“…Obesity and T2DM are closely related and difficult to control by current medical treatment, including diet, drug therapy and behavioural modification. [4][5][6] Bariatric surgery is the most effective treatment of morbid obesity and, depending on the type of operation, is also very effective in the resolution of diabetes. 7 This effect usually occurs even before the start of weight loss owing to changes in the gut hormones and the patient's diet.…”

Genetics of type 2 diabetes

“…Even within the same broad environment, individuals vary greatly in their adoption of unhealthy lifestyles and their willingness to change such lifestyles. By influencing who adopts a more unhealthy diet (this includes genetic influence on taste and food preferences), who exhibits greater willingness to change unhealthy behaviors [75] , who burns more calories at rest, who exhibits greater activity levels when not actively exercising, what kind of microbiome an individual carries, and who opts for a more sedentary lifestyle, genetic factors can play a role in determining who becomes obese or develops diabetes in any given environment [76] . These gene-environment interactions may be extremely complex and may be one reason why such a small proportion of the heritability of T2D has been explained at this time [77] .…”

An Analysis of the Physical Activity and Eating Behavior of College Students

“…The only category that did not show between-group differences was walking, which is probably because, due to large university campuses, students living within a university usually have to walk for more than 10 minutes per day. The fact that there are no differences in eating behavior between the two groups indicates that, since obesity is closely linked to heredity factors [6], the point that there are people who constitutionally do not gain weight despite overeating should be considered. Regarding diet, since an individual's hereditary or family history is important, calorie regulations should be encouraged for subjects with a predisposition to obesity.…”