Weight-loss is a fairly simple process involving a moderate daily caloric restriction and increased physical activity. To lose weight, you need to achieve a negative energy balance, or a state in which the calories you expend through activity exceeds the number of calories you consume through food. One pound of body fat equals 3,500 calories, so for every 1 pound of fat you aim to lose, you must reach a negative energy balance of 3,500 calories. You can still lose weight after the age of 40, but factors such as body composition and decreased metabolic rate may influence the amount of calories you can consume.
Your daily caloric needs are based on your basal metabolic rate, or the number of calories your body requires to perform basic vital functions, such as regulating body temperature, as well as your typical daily activity level. The US Department of Agriculture estimates that a moderately active female around the age of 40 requires about 2,000 calories a day, while a male of the same age needs closer to 2,500.
The maximum rate at which you can safely expect to lose weight without also inducing dehydration, nutrient deficiency and losses in muscle rather than fat, is about 1 to 2 pounds of body fat each week. You achieve a negative caloric balance of 3,500 calories, and a loss of 1 pounds of body fat, by restricting your diet by 500 calories each day. Based on the calorie estimations from the USDA, a moderately active female around the age of 40 needs to limit her caloric intake to about 1,500 a day, while a 40-year-old man needs to consume about 2,000.
You'll lose weight by cutting calories from your diet, regardless of the source of these calories. Nevertheless, your body still needs a sufficient amount of the three macronutrients to maximize energy metabolism. According to the Food and Nutrition Board of the Institute of Medicine, adults 40 and older should consume 45 to 65 percent of their calories from carbohydrates, 20 to 35 percent from fat and 10 to 35 percent from protein. A typical moderately active female around 40 should consume about 206 grams of carbohydrates, 46 grams of fat and 84 grams of protein when on a diet. A man of the same age and activity level should consume about 275 grams of carbohydrates, 61 grams of fat and 113 grams of protein when dieting.
You can greatly increase your caloric expenditure and the rate at which you lose weight by increasing your daily physical activity level. Exercise has the added benefit of increasing your basal metabolic rate and your body's energy needs as well. According to the USDA, adults over 40 need a minimum of 150 minutes of moderate-intensity aerobic exercise each week such as jogging or cycling. Exercising at this intensity burns up to 1,050 extra calories each week.
Changing Your Diet
According to the USDA, the number one source of calories for adults over 40 is grain-based desserts. While weight-loss is a result of caloric balance, regardless of the source, the type of food you eat indirectly makes weight-loss very difficult. Diets high in sugar adversely affect blood glucose levels and provide empty calories that keep you feeling hungry and ultimately lead to diabetic symptoms. Diets high in saturated fat and cholesterol leave you feeling sluggish and wreak havoc on the cardiovascular system, making exercise very difficult. Adults over the age of 40 should consume plenty of complex carbohydrates, unsaturated fats, fruits, vegetables and foods high in fiber to achieve their weight-loss goals.