How Burning the Fat Can Put a Smile on Your Face
Obesity, Thermogenesis,
and the MONA LISA Effect

Leonardo da Vinci, Mona Lisa,
ca. 1504

f all the obese people lost all their excess fat, one could make a decent-sized island out of it - but it would be too slippery to inhabit. Fortunately for the environment, fat isn't lost in the form of fat molecules anyway. Instead, these molecules are decomposed, through a process called lipolysis, into simpler molecules, mainly water and carbon dioxide. When lipolysis occurs, some of the chemical energy contained in the fat molecules is converted to thermal energy, or heat.

That conversion is an example of thermogenesis, which is defined as the generation or production of heat, especially by physiological processes. Another thermogenic process is the rapid conversion of some of the food we eat to heat, before it has the chance to be stored in the form of fat. This conversion is the process by which the body "wastes" calories, thus tending to resist weight gain. (Calories, of course, have no substance in and of themselves; they are merely a physical measure of thermal energy.) As we will see below, there are ways to boost thermogenesis so as to waste calories, burn fat and prevent fat gain.

Under normal circumstances, how many calories get wasted (excreted, in a sense) depends on the person's metabolic rate, which is one indicator of the likelihood of obesity in that person. All else being equal - which, of course, it never is - a high metabolic rate is characteristic of lean individuals, in whom as much as 40% of the caloric value of a meal may go to waste. A low rate is characteristic of obese individuals, in whom caloric waste may be only 10% or less, with much of the food's remaining chemical energy being stored as fat instead of being quickly converted to heat.1

It is important to clarify that we want to lose fat, and not weight per se (which is comprised largely of fat, muscle, and bone). As we age, it is fat that gains the upper hand, not muscle. Any weight-loss program (most diet plans) results in the loss of a significant amount of muscle, or lean body mass, along with the fat. This is especially bad in those over the age of 30, for whom it is very difficult to add additional muscle. Considering that most diets do not work - 95% of all weight lost via diets is regained within one year - what we end up with is a shift in body composition to a higher percentage of fat. This is worse than not having dieted at all.

Obesity is being way too fat. A better definition is being more than 20% above the normal, desirable weight for one's height. That can be misleading, however, because an athlete, e.g., can appear to be significantly overweight by having big muscles but with little fat - so he's not obese. Probably the best definition of obesity is having a body-fat percentage greater than 25% for men and 30% for women.

A common measure of obesity is body mass index (BMI), which provides a rough measure of health and life expectancy. To calculate your BMI, divide your weight in pounds by the square of your height in inches, and multiply the result by 703. (In metric units, divide your weight in kilograms by the square of your height in meters.) The ideal range is about 19-22. A value in the 25-29 range indicates overweight, a moderate threat to your health and longevity; a value of 30 or more indicates obesity, a serious threat (see Table 1).

Table 1. Body mass index (BMI) is a rough measure of your health and life expectancy. The ideal range is about 19-22. The lightly shaded area (25-29) indicates overweight, a moderate threat to your health and longevity; the darker area (30+) indicates obesity, a serious threat. To calculate BMI, divide your weight in pounds by the square of your height in inches, and multiply the result by 703. (In metric units, divide your weight in kilograms by the square of your height in meters.)

To discuss all the health liabilities associated with obesity would fill a book, so here is just one: In a recently completed, long-term study of a nationally representative sample of the United States population of men and women in the age range 25-74, it was found that body mass index is strongly correlated with the incidence of colon cancer.2 This disease is the third-largest cause of cancer mortality in both men and women, after lung and prostate cancer in men, and lung and breast cancer in women. It is notorious for metastasizing, or migrating, to the liver, at which point it is almost always inoperable and terminal.

As a rule, obesity is caused by some combination of genetic predisposition and behavior that can be self-indulgent, uninformed, unconscious, or self-prescriptive (mood control). As difficult as it is, we can change our behavior, but we cannot, yet, change our genes so as to avoid the tendency to obesity. What we can do, however, is combat some ofthe effects of our genetic programming, with supplements.

The most common genetic factor in obesity is a low level of activity in the sympathetic nervous system, which controls many of the body's most critical functions, including metabolism. (In physiology, sympathy refers to a relationship between body parts or organs by which a disease or disorder in one induces an effect in the other.)

There are ways to boost thermogenesis
so as to "waste" calories,
burn fat and prevent fat gain.

In preparing the body for strenuous activity (the "fight or flight" response), the sympathetic nervous system acts to increase heart rate, contract blood vessels, and reduce digestive secretions, among other things.3 This sympathetic system is essentially the opposite of the parasympathetic nervous system, which tends to increase digestive secretions, reduce heart rate, and dilate blood vessels.

As a complementary pair, these two systems constitute the autonomic nervous system, which controls the body's involuntary functions. The autonomic system is but one part of the peripheral nervous system, which is one of the two main systems - the other being the central nervous system - that govern all bodily functions.

Nerve impulses in the sympathetic and parasympathetic systems are mediated by the neurotransmitters noradrenaline and acetylcholine, respectively. Ideally, the two systems operate in a fine balance, with neither predominating. But when the balance is skewed toward a chronically low sympathetic nervous system activity, the result may be reduced thermogenesis and an increased stimulation for food intake - a recipe for obesity.

the active component in Ephedra, is well
established as an effective fat-loss agent,
especially in combination
with the alkaloid caffeine.

The hypothesis that this condition is, in fact, a characteristic feature of obesity (at least in most of the animal models that physiologists study) has been given the name "Most Obesities kNown Are Low In Sympathetic Activity," or MONA LISA for short.4 (Who says that scientists aren't cultured?)

A practical approach to the problem - besides diet and exercise, which are always the first priority for weight loss, but very hard to do - is to take supplements that boost sympathetic activity and thus thermogenesis. Substances that do this are called sympathomimetic agents. One such is ephedrine, which stimulates the release of noradrenaline.

Among the most ancient, and scientifically validated, herbal supplements is ephedrine (the active ingredient in Ephedra), a mild, slow-acting, nonaddictive alkaloid derived from shrubs of the genus Ephedra, which is native to China (where it is called ma huang) and India (where it was called soma, according to some research5). It has been used as an herbal extract for thousands of years, but it is now more commonly used as the pure synthetic compound, mainly to treat bronchial asthma, suppress allergic reactions, and relieve nasal congestion due to hay fever and respiratory infections.

Ephedra and alkaloid caffeine promote
the loss of fat but not of muscle mass.

Ephedrine is also well established as an effective fat-loss agent, especially in combination with the alkaloid caffeine, a central nervous system stimulant that also acts as a circulatory, respiratory, and digestive-system stimulant. Ephedrine (or Ephedra, its herbal version) and caffeine work synergistically, both in central (brain-level) suppression of appetite and in peripheral stimulation of thermogenesis.6-9 A key benefit of their action is that it promotes the loss of fat but not of lean muscle mass.10 The combination is also kNown (remember MONA LISA) to be an energy booster that increases physical performance during exercise.11,12

A good way to get ephedrine is through a standardized Ephedra and caffeine formulation. Those who prefer could try a supplement which also contains 5-hydroxytryptophan, a precursor to the vital neurotransmitter serotonin. It is believed that genetically induced serotonin deficiency is another common factor in obesity, and there is no doubt that this compound has a major influence on eating behavior.13 By boosting serotonin levels, 5-HTP helps reduce carbohydrate cravings.

In the Battle of the Bulge, there are some winners and, alas, many losers. To be a winner, make an Ephedra/caffeine dietary supplement a part of an integrated diet and exercise program. If there's one thing that virtually all health professionals agree on, it's the tremendous value, to people of all ages, of regular exercise - not just for weight control, but for so many other aspects of health and well-being that it's the closest thing there is to a panacea.

A word of caution: The most common side effects of ephedrine are insomnia, anxiety, and rapid heart beat. In large doses it can cause more serious symptoms, such as cardiac arrhythmias (irregular heart beat) and a sharp increase in blood pressure. People with heart disease, hypertension, diabetes, hyperthyroidism, seizures, Parkinson's disease, glaucoma, or enlarged prostate should not use ephedrine except with their doctor's approval.

Start slowly, with both supplements and exercise, and don't be surprised to see that your desire to maintain your new program is stronger than in the past. Caution: If you have any kind of medical problem - especially a heart problem (see sidebar) - or are very out of shape or technically obese, see your doctor before initiating a diet/exercise/supplement program, to gain assistance in designing a program that suits your unique needs. Best of luck, and may you smile like MONA LISA as you watch the pounds fade away.


  1. Laville M, et al. Decreased glucose-induced thermogenesis at the onset of obesity. Am J Clin Nutr 1993;57:851-6.
  2. Ford ES. Body mass index and colon cancer in a national sample of adult US men and women. Am J Epidemiol 1999; 150(4):390-8.
  3. Astrup A, Lundsgaard C. What do pharmacological approaches to obesity management offer? Linking pharmacological mechanisms of obesity management agents to clinical practice. Exp Clin Endocrinol Diabetes 1998;106 Suppl 2:29-34.
  4. Bray GA. The MONA LISA hypothesis: most obesities known are low in sympathetic activity. In Oomura Y, Tarui S, Inoue S, Shimazu T (eds.), Progress in Obesity Research, John Libbey & Co. Ltd., London, 1990, pp.61-6.
  5. Mahdihassan S, Mehdi FS. Soma of the Rigveda and an attempt to identify it. Am J Chin Med 1989;17(1-2):1-8.
  6. Astrup A, Toubro S, Cannon S, Hein P, Madsen J. Thermogenic synergism between ephedrine and caffeine in healthy volunteers: a double-blind, placebo-controlled study. Metabolism 1991 Mar;40(3):323-9.
  7. Dulloo AG, Seydoux J, Girardier L. Peripheral mechanisms of thermogenesis induced by ephedrine and caffeine in brown adipose tissue. Int J Obes 1991 May;15(5):317-26.
  8. Astrup A, Toubro S. Thermogenic, metabolic, and cardiovascular responses to ephedrine and caffeine in man. Int J Obes Relat Metab Disord 1993 Feb;17 Suppl 1:S41-3.
  9. Astrup A, Breum L, Toubro S. Pharmacological and clinical studies of ephedrine and other thermogenic agonists. Obes Res 1995 Nov;3 Suppl 4:537S-540S.
  10. Astrup A, et al. The effect of ephedrine/caffeine mixture on energy expenditure and body composition in obese women. Metabolism 1992;41:686-8.
  11. Bell DG, Jacobs I, Zamecnik J. Effects of caffeine, ephedrine and their combination on time to exhaustion during high-intensity exercise. Eur J Appl Physiol 1998;77:427-33.
  12. Bell DG, Jacobs I. Combined caffeine and ephedrine ingestion improves run times of Canadian Forces Warrior Test. Aviat Space Environ Med 1999;70:325-9.
  13. Wurtman RJ, Wurtman JJ. Brain serotonin, carbohydrate-craving, obesity and depression. Adv Exp Med Biol 1996;398:35-41.

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