We need a new approach to health and fitness-one that places less emphasis on body weight (or body fat) and more emphasis on healthy metabolism-becoming “metabolically” fit. To achieve “metabolic fitness” does not require having a lean body, nor does it depend upon having the cardiovascular system of an endurance athlete.
In scientific/medical terms, metabolic fitness can be defined in terms of how the human body responds to the hormone insulin. “insulin sensitive” bodies tend to have excellent glucose tolerance, normal blood pressures and heart-healthy blood lipid profiles. Therefore, insulin sensitive people tend to be at a lower risk for type II diabetes and heart disease than people who are “insulin resistant”- a metabolic condition in which the body’s cells (mainly those in skeletal muscle, liver and adipose tissue) don’t respond normally to this hormone and which ultimately may result in disordered lipid metabolism and elevated blood pressure.
Insulin resistance is associated with high risk for type II diabetes and heart disease.Although genes play a role, the major causes of insulin resistance are lack of exercise and consuming a diet high in fat (especially saturated fat) and refined sugar and low in fibre-a description that fits many peoples. Because these behaviours also promote obesity, the “insulin resistance syndrome” (also known as the “metabolic syndrome”) is observed more often in fat people than it is in thin people. But as i have pointed out already, a fat person with the metabolic syndrome does not have to become lean in order to become insulin sensitive (i.e., obesity is not have to be obese to be insulin resistant. So many non-obese men and women in the world are insulin resistant and don’t realise it.
Substantial improvements in insulin sensitively can be changed in a matter of days or weeks, which explains why dramatic improvements in glucose tolerance, blood pressures and blood lipids can be observed so quickly after starting an exercise programme or eating healthier foods. If we can accept the fact that metabolically fit and healthy bodies can come in all shapes and sizes, then the public health message becomes quite simple: be more physically active and consume a healthier diet.
As for exercise, moderate-to-vigorous activity (heart rate in the range of ~60-75 percent of maximum) for ~20-40 minutes per day on most days of the week is suitable for improving metabolic fitness (9,23). Intensity and duration of exercise can be modified to suit individual needs. If time is not a constraint, duration can be emphasised while exercising at the lower end of the intensity range.
Just as effective, however, is high-intensity exercise of only 20-30 minutes duration. As for nutrition, the best foods to boost metabolic fitness are those you find primarily near the food guide pyramid: whole grains, fruits and vegetables and legumes (beans). These foods have plenty of fibre and have been shown to improve health regardless of weight and independent of weight loss.