We will examine the relationship between exercise, obesity, and weight control. Obesity refers to the excessive accumulation of body fat. The problem of obesity and weight control is very complex. It includes many variables such as genetics and cultural factors as well as traditional energy balance equation. Globally obesity is an epidemic. In our country, more than 35% of our population is either overweight or obese. The percentage is on a rise at a very fast rate. These statics’ are alarming and are also associated with the health-related issues of obesity.
Health-Related Issues Of Obesity
- Type 2 diabetes
- Cancer risk
- Mood disorder
- Heart disease
- Reproductive disorder
- Liver disease
Further estimated medical cost and loss of work productivity due to absenteeism exceeds billions of rupees every year. But let me remind all that obesity is a modifiable risk factor.
Finding The Culprit
Adipose cells are the culprits where the fat is stored. There are various ways in which we can measure and estimate an individual’s body composition including body fatness. Currently, the best way medically adopted is called DEXA. DEXA stands for Dual Energy Xray absorptiometry. This imaging system allows the assessment of total and regional body fat as well as bone density.
Based on total body fat, men who have greater than 25% and women who have greater than 35% body fat would be considered obese. Most accurate DEXA instruments are very expensive and are not readily accessible to the general public. Less expensive and adopted in field methods are skinfold calipers in conjunction with measurement of hip and waist circumferences that can be used to estimate body fat. Other techniques include hydrostatic or underwater weighing, using electrical impedance and air displacement plethysmography.
For convenience and large-scale epidemiological studies, it is convenient to use Body Mass Index or BMI (Calculate your BMI here) as an estimate of body fatness. It is simply calculated by dividing weight in KGs by your height in meters squared. A BMI over 25 is considered to be overweight, while a BMI over 30 will put one in the obese category. Though easy and convenient, the accuracy of BMI in estimating body fatness is a concern. Based upon the BMI, many fit athletes may be put in the category of obese. This is because BMI does not take into account that a large amount of overall body mass can be in the form of muscle and not fat.
Visceral And Subcutaneous Fat
From a health perspective not all fat is the same. Upper body fat primarily in the abdominal region puts an individual at much greater health risk. More specifically it is the visceral fat located within the abdominal cavity that surrounds important internal organs such as the liver, pancreas, and intestines that provides the greater health risk. Lower body fat which is primarily subcutaneous carries a significantly lower health risk.
The health risks include the various components of what is known as metabolic syndrome. Metabolic syndrome is a cluster of conditions that include the following:-
- Raised blood pressure
- Increase in insulin resistance
- Atherogenic dyslipidemia
- Pro-inflammatory state
- Pro-thrombotic state
- Visceral obesity
These all can occur together due to obesity leading to cardiovascular disease, stroke, and Type 2 diabetes.
Understand the energy balance equation
Weight gain leads to overweight and obesity when an individual is in a chronic state of positive energy balance. Thus if the calorie or energy intake exceeds one’s energy expenditure over a prolonged period of time, weight gain and fat mass will increase. Such weight gain generally occurs gradually over many years if left unchecked. Weight loss will only occur if a chronic state of negative energy balance can be maintained. This can be accomplished by reducing one’s caloric intake or dieting, increasing one’s expenditure through exercise, or a combination of both factors.
The Working Of Weight Loss
Dieting alone can generally produce some weight loss initially, but unfortunately, most of it is due to loss of water not fat. Over time the majority of weight loss will be in the form of fat but also noticed that a significant amount of protein is lost usually from skeletal muscle. This is problematic as skeletal muscle is the major contributor to resting metabolic rate which in sedentary individuals can amount to 75% of the total daily energy expenditure. Thus dieting alone can reduce one’s Resting Metabolic Rate (RMR) making it difficult to keep the lost weight off. This is one reason why 90 to 95% of all individuals regain their weight when weight loss is accomplished by dieting alone.
The other component of the energy balance equation is that of Total Daily Energy Expenditure. RMR makes up to a larger daily contribution of 60 to 75% of TDEE. For individuals who exercise regularly, the physical activity component will be on the higher side of 15 to 35% of TDEE. This pushed RMR contribution to a lower 60% range. An inverse relation exists between TDEE and obesity. The greater TDEE is, the lower is the prevalence of obesity.
As the number of calories burnt during exercise varies depending on exercise intensity and duration; engaging in exercise alone without decreasing caloric intake may not be sufficient to achieve a constant negative energy balance, thus significant weight loss. A number of overweight and obese individuals, when beginning an exercise program become frustrated when they do not see any change in their weight between 1 to 3 months. Because of their weight and fitness level, these individuals cannot exercise at higher exercise intensities or for longer durations. As such the number of calories burned while exercising is relatively small. The optimum method to achieve and maintain a negative energy balance and thus weight loss is from a combination of dieting and exercise. It is observed that if this combination is adopted, almost all the weight loss is due to fat loss and at times results in the gain of lean body mass. Exercise stimulus prevents muscle loss typically associated with dieting alone and also prevents a drop in RMR. This greatly enhances one’s ability to maintain weight loss over time.
A Word From H2FCare
Even if overweight or obese individual do not lose a significant amount of weight while engaging in regular exercise, they still receive many of the health benefits by reducing risks of heart disease, diabetes, and some cancers thereby decreasing their overall risk of all-cause mortality.