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Weight management is a medical concern right now

Stephen Kreitzman
PhD RNutr
UK Registered Nutritionist

Valerie Beeson
Howard Foundation Research Ltd
Cambridge

What will it take to get more medical professionals to pay attention to the weight loss needs of their patients? Obese people cannot wait for the development of means to correct genetic defects, even if the recent highly publicised genetic findings are valid. There have been many reports of "obesity genes" discovered in the past. In fact, the problem does not appear to be finding genes associated with obesity, but the fact that there are already too many such genes. The evidence suggests that many of the people who are currently obese will die from the consequences of diabetes before genetic findings bear promising fruit.(1) Chronic obesity can lead to insulin resistance and ultimately to type 2 diabetes. The risk is said to be 50-fold greater for developing type 2 diabetes in the morbidly obese. The increase in risk, however, begins even below a body mass index (BMI) of 25.

There are so many articles in the medical literature relating overweight and obesity to the exacerbation of serious medical problems that it has become easy to ignore the opening paragraph clichés and get on to the juicy bits - which drugs to prescribe. The public, however, is being given poor information daily by the media. One of the worst pieces of information that is repeatedly propagated, even by professionals, is the admonition to solve the problem of obesity by reducing daily intake by 100-200 calories a day.2 It sounds so logical because you can multiply 200 calories by 365 and get a figure that represents almost 21 pounds of weight loss in a year.

The flaw in the argument, however, is that most overweight and obese people are not in calorie equilibrium, a condition that must be met for the calculation to be valid. Most obese people are exceeding their energy expenditure on a daily basis by hundreds, if not thousands, of calories. Reducing this excessive intake by a modest amount may slow the weight gain by a small degree, but will not result in a continuous loss of weight. The failure to lose weight almost certainly leads to a rapid abandonment of the method and a return to previous levels of intake. Losing weight requires a large enough calorie gap - the difference between the calories eaten and the calories used - to provide a real loss of weight in a time frame consistent with sustaining motivation. All the powerful biological instincts, the result of centuries of natural selection, are in play to encourage the acquisition of food. Survival depended upon getting enough food and eating enough of it to cope with the potential of long periods of famine. Those who were unable to acquire enough food and store calories in the body simply did not survive. The point is that you cannot expect patients, however well motivated, to sustain prolonged abstinence from food. The body is perfectly capable of relinquishing all the necessary calories from fat depots, at whatever rate is required, as long as the remaining essential nutrients are available. The need to advocate a minimal calorie gap is a myth. Achieving weight loss success requires as close to maximal rates of weight loss as the provision of essential nutrients will allow.

Fat loss and weight loss are not the same thing. Diuretics cause weight loss. Sweating causes weight loss. Neither cause fat loss. Experience with carbohydrate-restricted diets has demonstrated dramatically that there is a decisive loss of stored glycogen and its associated water before any substantial loss of fat.(3) Losing a pound of glycogen and associated water requires a deficit of about 360 calories. Losing a pound of fat requires a deficit of 3,500 calories. While thin people normally maintain a body store of glycogen representing between five and 15 pounds of weight, fat people, who store glycogen in fat cells as well as liver and muscle, can have a body store in excess of 15 kg (33 pounds).

Reducing the body fat mass, the real object of weight management requires much more substantial loss of weight than is achieved by token calorie deficits. It should come as no surprise that modest weight losses are rapidly regained. Repletion of stored glycogen and its associated water is physiological. It is time to stop treating weight management as if it was simply a matter of a few minutes of exercise or reducing a few calories of intake a day. The consequences of avoiding effective weight management are life-threatening for the patient.

References

  1. Parental role in ending child obesity. General Practitioner 2005;11:38.
  2. Chappell DA. The link between obesity and diabetes. Are you at risk? Healthy Living. Available from: http://www.arguscourier.com
  3. Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: illusions of easy weight loss, excessive weight regain and distortions in estimates of body composition Am J Clin Nutr 1992;56:292S-3S.