Obesity and Lifestyle Changes
Did You Know That?
Aggressive long-term diet and exercise regime (as in the Look AHEAD Trial) can result in less need for insulin treatment, can reduce central adiposity (belly fat), A1C (improved glucose control), advanced kidney disease and many other heart attack (cardiovascular) and stroke risk factors but may not reduce heart attack or strokes.
The non-reduction in the heart and stroke events, even though they improve risk factors for heart attacks and strokes such as hypertension, diabetes, metabolic syndrome, insulin resistance, lipid (cholesterol) profile, is most likely because these risk factors would have been operating for decades, during which time they would have caused significant damage to the blood vessels. The longer an individual had had these risk factors, the more likelihood that sustained irreversible damage would have taken place within the individual’s arteries (blood vessels), that would ultimately lead to higher levels of sustained chances of heart attack or stroke.
However, when these risk factors have been present for shorter durations of time, some, if not all the damages to the arterial walls could be reversed by lifestyle changes such as weight loss, diet and exercise. The family of cholesterol lowering medications known as the ‘statins’ play a proven and significant role in the reversal, regression and/or stabilization of these changes in the blood vessels. They have been seen in numerous good quality medical research to confer significant protection to heart attack and stroke to individuals with these heart attack and stroke risk factors and with atherosclerosis (damage to blood vessels).
Exercising daily without caloric restriction could be associated with significant reductions in total body fat, visceral fat, abdominal fat, insulin resistance in both men and women. Exercise in the absence of accompanying weight loss can result in significant loss of total body fat and abdominal fat (obesity). Most people who exercise especially when the exercise involves weight bearing such as jogging, walking, resistance exercises gain lean body mass and may lose equivalent fat mass resulting in Zero net body weight loss. In weight loss programs where exercise and caloric restrictions constitute the principal means of weight loss process, it is therefore necessary to employ efficient and reliable measures to determine changes in body composition - fat mass loss and muscle mass gain or loss.
Such measurements can be obtained with calipers for skinfold measurement, Gulick tape for weight circumference measurement or a reliable and reproducible body composition machine.
One hour of daily moderate aerobic exercise results in as much fat mass loss as equivalent caloric restriction.
The addition of resistance exercise to energy restriction (dieting) does not appear to prevent the expected loss of fat-free mass (muscle or lean body mass) that is typically associated with caloric restriction (or dieting). The combination of resistance exercise and caloric restriction also prevents the expected reduction in basal metabolic rate or the resting energy expenditure (typically associated with weight loss not accompanied with resistance training).
A total of 7-10 miles of walking each week will prevent deteriorations in lipids (cholesterol) associated with inactivity.
Exercise that involves significant resistance load such as resistance exercise training may result in several pound increase in muscle mass which can somewhat offset decreases in volume of fat mass loss.
When a sedentary overweight person engages in a walking exercise program he/she can gain lean muscle mass in the weight bearing muscles of the lower extremities (the buttocks, thighs, legs and feet). A person can burn significant energy by carrying backpacks. Energy expenditure by the individual will be proportional to the weight of the backpack the length of time and the type of terrain (the gradient of an uphill trail vs a downhill trail). The intensity of such an activity (with the backpack) will result in increased muscle mass in the trunk, the flexor muscles and extensor muscles of the lower extremities. In other words, the increase in muscle mass in these muscles will be proportional to the intensity of the activity such as the weight of the backpack, time and distance walked and the type of terrain involved (uphill vs downhill).
When we roll our bags (luggage), we expend a whole lot less energy than when we carry the equivalent weight bags.
To be more precise in determining the effects of an activity such as carrying a backpack, one will need to consider the net vs gross energy expenditure/cost of the activity. The net energy expenditure is the gross energy expenditure minus the index exercise or activity related energy expenditure. The gross energy expenditure includes the energy expenditure accounted for by the individual’s basal metabolic rate or resting energy expenditure (which is the calorie expended by the individual’s body to maintain his/her body function such as respiration, cardiac/heart activity cellular functions etc.) The basal metabolic rate, on the other hand is influenced by the person’s body size (heavier people tend to have higher basal metabolic rate)