- Health & Wellness
- Dr. Frischer
- 412 views
Whether your goal is to lose weight, gain weight, or maintain your current weight, you may have asked your doctor: "How many calories should I consume?" That sounds like a simple and straightforward question. Your doctor's answer, however, might not be useful: "Well, that depends on many factors." Today, let's tackle the impossible and try to provide something fairly simple to hang your hat on.
First, let's admit that the number of calories you should consume does in fact depend on several factors, including age, weight, height, gender, lifestyle, and overall health. It's obvious, for example, that a physically active 22-year-old six-foot tall man requires many more calories than does a five-foot tall sedentary woman in her 70's. Even the way we eat and when we eat likely affects how many calories we retain. Those who chew longer actually hold onto more calories. A big breakfast may be helpful for weight loss. (This is controversial. The idea is that by eating a sensible breakfast we reduce hunger for the rest of the day; by eating a meal we tend to avoid unhealthy snacks; and by eating breakfast we have more energy, leading to increased physical activity.)
We eat because our human body requires energy. About 20% of the energy goes to the brain, and most of the rest is used for basal metabolic requirements (energy required simply to maintain our blood circulation and breathing). In cold weather, our metabolism increases to produce more heat to maintain a constant body temperature. When in warm weather, we require a lower base level of energy.
A calorie represents the amount of energy provided by food or drink. Protein and carbohydrates provide four calories per gram, while all fats have nine calories per gram. How many calories do we actually need? The first step is to calculate our BMR (basal metabolic rate):
BMR for adult men = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age)
BMR for adult women = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age)
Next, let's modify our BMR to account for our level of activity. Those with a sedentary lifestyle, with very little exercise, will multiply the BMR by 1.2. That multiplier will increase up to a maximum of 1.9 for those with an extra active lifestyle. (For further detail, look up the Harris Benedict Equation.) This adjusted BMR represents the approximate number of calories we should consume each day to maintain our current weight.
Now that we have calculated our own Basal Metabolic Rate (calories needed per day), adjusted for activity level, how do we estimate our ideal target weight? There are many methods, but the most widely adopted is the BMI (body mass index):
BMI = Weight in pounds / (height in inches, squared) x 703
In general, adult men with a BMI of less than 18.5 are considered underweight, between 18.5 and 25 is ideal, 25 and 30 is classified as overweight, and over 30 obese. Women naturally carry more body fat, but men carry more muscle mass. As a result, the ideal BMI for most women runs lower than the ideal BMI for most men.
BMI is a widely used measurement and is gaining in popularity and importance. However, it certainly has shortcomings. It doesn't take into account waist, chest, or hip measurements. It ignores activity level, and doesn't take into account bone density (bone mass), body type, gender, and age.
We now have a feel for the approximate number of calories needed, based on activity level, to maintain our weight. We also can gather, from our BMI, whether we are above, at, or below our ideal weight. Consider adding or subtracting 200 - 400 calories from your daily food and drink, depending on your goal. Think about how you want to divide up this number of daily calories among meals and snacks. Keep in mind that certain foods, like a fast food burger, can have a major impact on your goal. Check the nutrition facts on food labels (or on menus) for calories, along with general nutrition content.
Most experts agree that it is more important to focus on eating a healthy and well-balanced diet and to be physically active, than to count the precise number of calories consumed. Indeed, counting calories can be difficult - note that a "growing" problem is portion sizes. Take the average cheeseburger: 20 years ago it averaged 333 calories, and today the average is closer to 600! Likewise, the "large" soda washing down that burger has been steadily growing in size over time.
Consuming the "ideal" number of calories is admittedly a tough task, and in this article I'm not addressing the lifestyle, health history, and psychological factors that make losing or gaining weight such an enormous challenge. Nor am I addressing what a huge impact that achieving an ideal weight can have on your health. These issues have been the topics of many prior articles. Perhaps these tools, however, can play a small part.
For more assistance, here is a handy USDA website that provides extra tools to help manage and regulate your daily calories: www.choosemyplate.gov/supertracker-tools/daily-food-plans.html
Dr. Alan Frischer is former chief of staff and former chief of medicine at Downey Regional Medical Center. Write to him in care of this newspaper at 8301 E. Florence Ave., Suite 100, Downey, CA 90240.
Published: Sept. 26, 2013 - Volume 12 - Issue 24