Scientists believe that each individual has a genetically determined weight variance of perhaps 30 pounds. Are you shocked by this statement, published in The New York Times? Does it seem that diet and exercise form a futile struggle to defy the brain’s innate calorie counter? 
Is It All About the Food?
Over the past 10 years I have lost 100 pounds (45 kg), in 10-pound increments. Unfortunately, I have also gained as much weight. Americans have been getting larger for decades. Two thirds are now overweight.
In the 1960s, McDonald’s was popular enough to have sold billions of burgers; home-cooked meals had plenty of butter; and American apple pie with refined white sugar and a glass of whole milk for desert was a tradition. So the argument that the progressive increase in obesity is due to fast food consumption is debatable. As we step back, factors beyond nutrition come into view.
A noticeable change in the digital age is that nearly everything is delivered to our seats. The library, the theater, the concert, the mall, even grocery shopping are all accessible from our desktop or sofa. With tremendous health risks, technology has bred an increasingly sedentary generation. This has spawned the emerging field of “inactivity physiology.” 
Can We Burn All the Calories We Consume?
A basic weight-loss principle is to burn more calories than we consume. For adults aged 18–64 the 2008 federal health guidelines state, “Adults should do 2 hours and 30 minutes a week of moderate-intensity, or 1 hour and 15 minutes (75 minutes) a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic physical activity.” 
A 20-minute walk burns about 100 calories. That’s 300 calories per hour. Recommended daily calorie consumption is 2129  (though many restaurant and processed foods include as much or more in a single meal). Therefore, one would theoretically require 7 hours of moderate exercise to burn 2100 calories. There are 3500 calories in a pound.  Unrealistic though it may be, it would seem that it would take around 12 hours of walking for the scale to register the loss of a pound. Are you wondering, “How could I ever burn more calories than I eat?”
Daily activities like gardening, washing your car or walking to the refrigerator burn another couple hundred calories. Vigorous workouts burn an additional 300–500 calories per hour. Add it up and you could be burning over 1600 calories a day before visiting the gym. Individual BMR can be calculated based on height and weight.  Once you calculate your BMR, consume less calories to decrease weight. (The BMR for my age, weight, height and gender is 1540, before exercising. —Ed)
Regular exercise also converts stored energy (fat) into muscle (which is heavier than fat). There are significant health benefits associated with cardiovascular exercise beyond weight loss. The processes involved with maintaining healthy weight are much more complex than just walking longer or, on the other extreme, dieting solely by BMR.
Genetics and Metabolic Syndrome
“There are physiological mechanisms that keep us from losing weight,” [1,7] said Dr. Matthew W. Gilman, the director of the obesity prevention program at Harvard Medical School/Pilgrim Health Care. Based on over 15,000 clinical studies, the protein hormone leptin  apparently triggers the brain to adjust metabolism, maintaining a genetically established weight range within about 30 pounds.
Eat less and the body conserves more fat. Increase food consumption in an effort to go beyond that innate barrier and the metabolism rate speeds up to compensate. Like a rubber band, most who dramatically deviate from their genetic weight often return after the extreme caloric deprivations or fulsomeness. These are the battles with which we all contend in order to achieve the ideal Body Mass Index goals of 18.5–24.9 BMI.
A nine-year study of 48,500 U.S. men and 56,343 U.S. women has shown that the larger your waistline, the higher the risk for mortality. 
Though exercise and healthy eating should not be diminished, biological factors contribute to weight management. The American Heart Association has outlined characteristics of metabolic syndrome,  where several etiologies converge with genetics. For managing both long- and short-term health risks, lifestyle therapies are the first-line interventions to reduce the metabolic risk factors:
- Abdominal obesity (excessive fat tissue in and around the abdomen)
- Atherogenic dyslipidemia (blood fat disorders—high triglycerides, low HDL cholesterol and high LDL cholesterol—that foster plaque buildups in artery walls)
- Elevated blood pressure
- Insulin resistance or glucose intolerance (the body can’t properly use insulin or blood sugar)
- Prothrombotic state (e.g., high fibrinogen or plasminogen activator inhibitor–1 in the blood)
- Proinflammatory state (e.g., elevated C-reactive protein in the blood)
Paring Down the Risks
A nine-year study of 48,500 U.S. men and 56,343 U.S. women has shown that the larger your waistline the higher the risk for mortality—in fact, obesity doubles the risk.  An easy goal to remember is to keep your waist size less than half of your height. Just figure out your height in inches and divide by two.  With that in mind, one would need to be 6-foot 7-inches tall to justify waistline of 40 inches.
Because genetics play a significant role in our physique, there will continue to be variations in man and woman body shapes. It’s not an excuse, but, for many, an obstacle with which to contend. Despite any biological weight barrier imposed by leptin and other physiological processes, we can be A Bit More Healthy with sensible meals and exercise, even if we do not achieve the ideal BMI.
Let’s face it, 30 pounds is a relatively wide range for variance. If we are at the high end of the scale, there is sufficient room to lose weight and keep it off. For morbidly obese persons, medical intervention can be discussed with the appropriate healthcare provider. Inaction is the worst response to obesity.
- Prevention: Doctor’s Weight Affects Obesity Diagnoses. The New York Times, March 19, 2014. For the Overweight, Bad Advice by the Spoonful. The New York Times, August 30, 2007
- New National Physical Activity Guidelines For Americans Recognize Emerging Longevity Research. Stanford Center on Longevity, November 16, 2018
- Physical Activity Guidelines for Americans 2nd Edition. Department of Health and Human Services, Health.gov
- Average calorie consumption, WolframAlpha.com
- Basal metabolic rate. Wikipedia
- BMR Calculator. BMI-calculator.net
- Leptin and the regulation of body weight in mammals. Nature, Vol 395, October 22, 1998, nih.gov
- What is Liptin? Wellness Resources, Byron Richards, January 12, 2009, wellnessresources.com
- Low HDL & Elevated Triglycerides are a Major Cardio Risk Factor. Wellness Resources, Byron Richards, September 11, 2009
- Metabolic Syndrome. American Heart Association, americanheart.org
- Waist to Height Ratio – Is your Stomach Too Large? Wellness Resources, Byron Richards, June 27, 2008, wellnessresources.com