Obesity is a complex, multifactorial disease that develops from the interaction between genotype and the environment. It involves the integration of social, behavioural, cultural, physiological, metabolic, and genetic factors. According to the Expert Panel, overweight is defined as a body mass index (BMI) of 25 to 29.9 kg/m2, and obesity is defined as a BMI ≥ 30 kg/m2. Classification of BMI is below-tabled
|Classification of BMI||BMI kg/m2|
|Normal weight||18,5 – 24,9|
|Overweight||25,0 – 29,9|
|Obesity class 1||30,0 – 34,9|
|Obesity class 2||35,0 – 39,9|
|Obesity class 3||>40|
Abdominal fat is an important, independent risk factor for disease. The evaluation of waist circumference to assess the risks associated with obesity or overweight is supported by research. Those diseases that denote high absolute risk are:
- type 2 diabetes mellitus
- established coronary heart disease
- atherosclerotic diseases
- breathing problems during sleep
Weight loss in Obesity and Type 2 Diabetes Mellitus
Obesity and diabetes are intimately linked. Obesity and in particular abdominal obesity is a major driver in the development of diabetes and cardiovascular disease, with the increasing prevalence of obesity mirrored by the rising prevalence of diabetes. In addition, obesity and overweight are associated with multiple comorbidities. Weight reduction, therefore, is a key therapeutic goal in both the prevention and management of type 2 diabetes. Weight reduction with intensive lifestyle intervention has been shown to reduce the incidence of diabetes by up to 58%. A combination of diet modification, increased physical activity, and behaviour therapy can be effective in weight reduction.
For individuals with diabetes, studies have shown that a loss of 5–10% of body weight can improve blood glucose control, improve cardiovascular disease risk factors, improve fitness, and decrease use of diabetes, high blood pressure, and fat-lowering medications. Additional benefits of weight loss include reduction of depression symptoms and remission or reduced severity of obstructive breathing problems during sleep.
Greater symptom improvements are observed with greater weight loss. Guidelines recommend lifestyle modifications as the foundation of weight loss. Long-term weight loss is still difficult to achieve for many patients, and alternative options, such as use of medications, should be considered for patients who cannot lose weight with lifestyle modification alone.
Although lifestyle interventions aimed at prompting weight loss are important in the management of type 2 diabetes and the benefits of weight reduction are irrefutable, most patients remain overweight or obese. For patients struggling to achieve or maintain their weight-management objectives, concomitant anti-obesity medications can be considered, with the aim of reducing patients’ body weight and blood glucose targets. Recent approvals of therapies that provide both blood glucose control and weight reduction provides a wider choice of therapy in the future.
Weight gain and Diabetes risk
Findings have demonstrated a significant association between weight gain and increased risk of diabetes in a sample of adults who are already overweight – a group at especially high risk of developing diabetes. These findings suggest that people who are overweight are susceptible to added diabetes risk after additional weight gain. This finding shows that weight gain in adulthood is associated with increased risk of developing diabetes.
Meanwhile, duration of overweight predicts diabetes risk and thissuggests that this factor may have cumulative effects. Other studies have shown a strong association between primary weight maintenance or moderate weight loss and decreased diabetes risk
Similarly, studies have shown that as many as 1 in 5 diabetes cases could be prevented if, at a population level, weight was maintained in adulthood. While primary weight maintenance in adulthood is challenging, it should still be considered in contrast to the even more difficult challenge of weight loss and subsequent secondary weight maintenance. The potential of primary weight maintenance in reducing diabetes risk is an important public health message, and a population-based approach to promote primary weight maintenance is desirable as a complement to targeting individuals at high risk.
In summary, there is great potential for diabetes prevention in promoting primary weight maintenance, in addition to moderate weight loss in individuals with a BMI ≥25.0 kg/m2 and the current approach of targeting interventions to individuals in high risk groups.
- Adina L. Feldman et al Impact of weight maintenance and loss on diabetes risk and burden: a population-based study in 33,184 participants BMC Public Health, 2017 accessed online at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5294882/ on 27/07/2019
- Resnick HE, Valsania P, Halter JB, et al, Relation of weight gain and weight loss on subsequent diabetes risk in overweight adults, Journal of Epidemiology & Community Health 2000;54:596-602.
- Luc Van Gaal and Andre Scheen , Weight Management in Type 2 Diabetes: Current and Emerging Approaches to Treatment, Diabetes Care Journal 2015 accessed online at https://care.diabetesjournals.org/content/diacare/38/6/1161.full.pdf