Weight management is the phrase used to describe both the techniques and underlying physiological processes that contribute to a person’s ability to attain and maintain a certain weight. Most weight management techniques encompass long-term lifestyle strategies that promote healthy eating and daily physical activity. Moreover, weight management involves developing meaningful ways to track weight over time and to identify ideal body weights for different individuals.
Due to the rising obesity rates in many parts of the world, proper weight management strategies most often focus on achieving healthy weights through slow but steady weight loss, followed by maintenance of an ideal body weight over time.
Rising Obesity rates are a major concern around the world, especially in North America. About 60% of Americans and Canadians are either overweight or obese. Understanding the basic science of weight management and some of the strategies for attaining and maintaining a healthy weight is very important to a person’s overall health because obesity is a risk factor for many chronic diseases like Type 2 diabetes, hypertension and cardiovascular diseases.
Our body weight is determined by the amount of energy that we take in as food and the amount of energy we expend in the activities of our day. Energy is measured in calories. Metabolism is the sum of all chemical processes within the body that sustain life. Your basal metabolic rate is the number of calories (amount of energy) you need for your body to carry out necessary functions. If your weight remains constant, this is likely a sign that you are taking in the same amount of calories that you burn daily. If you’re slowly gaining weight over time, it is likely that your caloric intake is greater than the number of calories you burn through your daily activities.
Every adult is in control of the amount of food he or she consumes each day, so our intake of calories is something we can control. To a major degree, we can also control our output of energy, or the number of calories we burn each day. The number of calories we burn each day is dependent upon the following:
- Our basal metabolic rate (BMR), the number of calories we burn per hour simply by being alive and maintaining body functions
- Our level of physical activity
For some people, due to genetic (inherited) factors or other health conditions, the resting metabolic rate (RMR) can be slightly higher or lower than average. Our weight also plays a role in determining how many calories we burn at rest — the more calories are required to maintain your body in its present state, the greater your body weight. A 100-pound person requires less energy (food) to maintain body weight than a person who weighs 200 pounds.
Lifestyle and work habits partially determine how many calories we need to eat each day. Someone whose job involves heavy physical labor will naturally burn more calories in a day than someone who sits at a desk most of the day (a sedentary job). For people who do not have jobs that require intense physical activity, exercise or increased physical activity can increase the number of calories burned.
As a rough estimate, an average woman 31-50 years of age who leads a sedentary lifestyle needs about 1,800 calories per day to maintain a normal weight. A man of the same age requires about 2,200 calories. Participating in a moderate level of physical activity (exercising three to five days per week) requires about 200 additional calories per day. More strenuous exercise programs, such as those with cardio focus, can burn even more.
How do you lose weight?
The best approach for weight loss is reducing the number of calories you eat while increasing the number of calories you burn through physical activity. To lose 1 pound, you need an expenditure of approximately 3,500 calories. You can achieve this either by cutting back on your food consumption, by increasing physical activity, or ideally, by doing both.
For example, if you consume 500 extra calories per day for one week without changing your activity level, you will gain 1 pound in weight (seven days multiplied by 500 calories equals 3,500 calories, or the number of calories resulting in a 1-pound weight gain). Likewise, if you eat 500 fewer calories each day for a week or burn 500 calories per day through exercise for one week, you will lose 1 pound.
Examples of calorie content of some popular foods and beverages include the following:
- One slice of original-style crust pepperoni pizza – 230 calories
- One glass of dry white wine – 160 calories
- One can of cola – 150 calories
- One quarter-pound hamburger with cheese – 500 calories
- One jumbo banana nut muffin – 580 calories
Any fitness activities you do throughout the day are added to your BMR (basal metabolic rate) to determine the total number of calories you burn each day. For example, a 170-pound person who spends 45 minutes walking briskly will burn about 300 calories. The same time spent on housecleaning burns about 200 calories, and mowing the lawn for 45 minutes consumes around 275 calories.