Wednesday, September 16, 2009

The Obesity "Epidemic" and Nutrition

There has been a lot of talk and newsprint about the obesity "epidemic" that is occurring, but I feel that certain facts have been ignored, as well as certain principles of human behavior. Whenever patients tell me that doctors don't know much about human nutrition, I generally comment that neither does anybody else. There have been very few double-blinded studies about the effect of nutrition on human health and well-being, but that doesn't seem to stop people from being more certain about human nutrition than the facts will allow:

1) No one knows how many meals a human should eat each day: one, six, or whatever.

2) No one knows at what time of the day the largest meal should be eaten, (but if you eat within 2 hours of bedtime you increase your risk of reflux esophagitis).

3) If you eat only vegetables, you will die from pernicious anemia, aka vitamin B-12 deficiency, since vegetable cells contain NO vitamin B-12; vitamin B-12 is is needed for animal cell DNA synthesis, and not for vegetable DNA.

4) Nobody smiles in a vegetarian restaurant, but everyone looks ecstatic at a steak restaurant such as Peter Luger's.

5) The only vegetables that seem to benefit human health when added to the diet are alcohol (beer, wine or whiskey), dark chocolate, olive oil (the Mediterranean diet), and the bark of the willow (salicylic acid, which Bayer transformed into aspirin).

6) No one knows how much water/fluids a human should drink each day, but the general consensus is a minimum of 0.5 liters, since that is the urine volume required to excrete the products of oxidation in maximally concentrated urine.

7) In a hospital, the minimum IV should be D5/0.5NaCl with 20 meq of KCl at 125 cc/hr, and then adjust to the patient's condition.

8) Fat cells require cholesterol and preferentially absorb insulin, so if you are a diabetic or have a cholesterol problem, you should lose weight.

9) Cholesterol does not increase cholesterol, so egg yolks are OK, and, in fact, eggs have about the highest protein per gram of any food.

10) If you do not have high blood pressure and are not diabetic, then salt and sugar should cause you no problem.

11) Almost all my patients who on oral medicine for diabetes cannot/will not lose weight, even after I tell them that a 20m pound weight loss will probably (temporarily) cure their diabetes.

12) As you get older, your metabolism slows up, and your blood pressure, cholesterol and fasting blood sugar generally increase.

13) Most women find it impossible to lose the last 5 pounds necessary to get down to their pre-pregnancy weight.

14) Most men gain at least 10-15 pounds the first year they work or get married, in the first case from lack of exercise (8-10 hrs/day behind a desk), and in the second case from an increase in calories consumed at dinner.

15) Cigarette smoking increases your metabolism and decreases your appetite, so most men gain 10 pounds the first year they quit smoking and most women gain 15.

16) And this is key: The first pleasure all humans got was from being fed, either at their mother's breast or from a bottle. The first desire to be fulfilled was that created by hunger. Therefore, it feels good to eat, and it is difficult to deny yourself this fundamental pleasure and to feel hungry, which you must do in order to lose weight. The first time a woman's dress goes from size 6 to size 8, or a man's belt from 32" to 34", they rarely say "I must lose some weight". It has nothing to do with not knowing how many calories they are eating, or doctor-patient information, or lack of electronic medical records. Most patients don't care enough about how they look after gaining 10 pounds, or believe that there is enough increased health risk from added weight to lose the additional pounds. Men actually are less stressed by their appearance when overweight than are women: When a woman looks full face into a mirror, she sees the added weight that went to her hips, but when a man looks in a mirror the same way, he barely sees the added weight that went to his belly.Losing weight means being willing to suffer present pain for future gain, and the human brain is not geared to worry about the future, but rather to fasten the seatbelt 10 seconds before the car hits a brick wall. The same comment about future gain also holds true for exercise, but the average patient finds it much easier to exercise than to lose weight.

17) I also think the reason that almost all humans love ice cream is that it is rich in sugar and fat, just like mother's milk.

18) Don't you think that by the time he/she is 7 days old, a baby is addicted to sugar by Pavlovian conditioning: whenever he/she is hungry (or whatever is felt), this discomfort is assuaged by a warm sweet fluid, so that the baby associates warmth (chicken soup?) and sweets with a sense of comfort and well-being. It's difficult to see how an external message can easily overcome this dependence.

19) Final observation: based on my informal questioning of my patients, the majority of adults who loved chocolate ice cream as a child can curl their tongue (I can!), while the majority of patients who did not like chocolate ice cream cannot. I wonder what the genetic linkage is. I personally thought that my friends who preferred vanilla ice cream to chocolate could not have possibly tasted the same chocolate flavor that I did.


  1. There are indeed few helpful studies for health effects of diet. Among the notable are three at Mayo from 1978 through 1983 testing the hypothesis that vitamin C improves cancer survival, all with null results. A 1996 study for vitamin E effects on heart disease showed reduction in infarction rate after one year, and a 2001 study of diabetics showed improvements in cardiac indices, while a 2002 study of effects on macular degeneration showed a null result. The 2009 Physicians Health study for both vitamins showed null results for several cancers. A 2003 study for effects of omega-3 fats on depression showed a null result, and a 2009 study for cardiac-associated mortality showed a null result.

    Other dietary factors can have effects. Strict control of dietary fat and cholesterol may reduce gallstones, although not everyone benefits. A 2004 study showed significant risk reduction for men. A 1996 study showed that a diet high in fiber and low in animal fat did not reduce risk of kidney stones more than increased fluid intake. A 2000 study of dietary fiber effects on adenoma showed a null result. A 2008 study for adult-onset diabetes showed better control with low gycemic index foods than with high-fiber foods.

    While needs for vitamins and other nutrients have been established by controlled studies, there are few reliable studies for effective quantities. Most controlled studies of diet factors have been of short durations with small populations. The mortality studies have very low predictive power, since few participants die during limited testing. Many studies focus on outcomes for people at high risk: after diabetes diagnoses, cancer treatments or heart attacks. Few address long-term preventive effects for the general population. There is need for better studies of diet factors, but there is very little government support for them.

  2. Of course, the real problem with all dietary studies is their brevity. A white lab rat reproduces every 30 days, so a six month study covers six generations. Humans reproduce every 20 to 25 years, so we never had an interventional study lasting one generation, let alone two, and we certainly never had an interventional study beginning at birth.

  3. A recent (May, 2011) article in Lancet reproducing a 30 year study of weight and health showed that in the Far East, heavier patients (BMI 26-29) had the best survival rate after a heart attack. No one knows what to make of this result.

  4. The Washington Post issue of June 29, 2011 quoted two studies, one from Carnegie-Mellon Institute and one from Cornell University , both of which stated that posting calories on a menu does not lead to weight loss, because the main problem seems to be a lack of self-control on the part of the eater. I am trying to get the two articles, but without proper subscriptions this seems to be impossible.