As we all know, obesity is now considered a pandemic. In the US, prevalence rates of obesity have almost doubled from 12.8% to 22.5% during the last couple of decades (Kuczmarski et al., 1994; Mokdad et al., 1999). Diet interventions or exercise alone has been unsuccessful in controlling obesity and the accompanying metabolic diseases. A combination of the two seems more appropriate in controlling obesity. Also, recent research reporting the role of insulin in causing the obesity syndrome has lead to the belief that decreasing insulin secretion may help weight loss. In fact, suppression of insulin in the absence of any dietary or exercise interventions seems to cause weight loss (Velasquez-Mieyer et al., 2003).
Thus, a combination of exercise, dietary interventions by reducing refined carbohydrates and intermittent fasting – all working towards suppression of insulin secretion and reducing circulating levels of insulin in blood – may likely be the best way to fight obesity.
Role of Insulin in Obesity
Obese people exhibit raised insulin levels in their blood – a condition called hyperinsulinemia (Haffner et al., 1996; Lillioja et al., 1991). Whether the raised levels are responsible for causing obesity or obesity causes raised levels of insulin is not known. Although it is not known whether raised insulin levels are a cause or effect of obesity, research does prove that hyperinsulinemia is associated with development of obesity (Le and Bougneres, 1994; Sigal et al., 1997; Taylor et al., 1994), increased calorie intake (Brandes, 1977), increased carbohydrate craving (Brandes, 1977) and a lethargic lifestyle (Cohen et al., 1986; Woods et al., 1974).
In humans, insulin is responsible for storage of excess calories in the form of body fat (Marin et al., 1987). Within the fat cells, insulin regulates fat metabolism by affecting the secretion of enzymes and genes:
- Enzyme acetyl-CoA carboxylase
- Enzyme lipoprotein lipase (promotes breakdown of fat – starvation seems to increase synthesis of this enzyme)
- Enzyme fatty acid synthase (promotes formation of fats)
- Expression of Glut4 gene (for Glut4 – a glucose transporter for fat cells responsible for carrying glucose into fat/muscle cells)
Effective Strategy of Weight Loss
As stated earlier, a combination of daily exercise, dietary interventions by altering the macronutrient content and intermittent fasting seems to the best way to induce weight loss. Scientific evidence in support of this seems to be overwhelming.
• Acute exercise – seems to stimulate glucose transporter proteins which otherwise need insulin for stimulation – such as occurs after a meal. Thus, glucose is transported into muscle cells; this process takes place without the need for increasing insulin secretion (Douen et al., 1990) Reduced circulating insulin levels ensure that excess calorie are not deposited as fat. Low levels of insulin for prolonged periods also increase insulin sensitivity. Thus, this can have an application in treatment of type 2 diabetes as well!
• Intermittent fasting – for example alternate day fasting – will also reduce circulating insulin levels and have effects mentioned above.
• Changing dietary macronutrient content – suppression of secretion and circulating levels of insulin seem to decrease carbohydrate craving (eating sugary things) and alter the intake of macronutrients (Velasquez-Mieyer et al., 2003), i.e., a person is more likely to eat proteinaceous food.
Thus, controlling insulin levels in your body seems to hold the key in suppressing obesity and its associated ill-effects. To conclude, a smarter, more effective and quicker way to lose weight and fight obesity would be to implement exercise and dietary interventions (decrease sugars and increase protein content of food) coupled with intermittent fasting.
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