CORRESPONDENCE: LETTER TO THE EDITOR
The Emperor’s New Clothes Are Loose: Lower Body Mass Index, Not Calorie Restriction, Accounts for Improved Diastolic Function
James B. Johnson, MD*,
Donald R. Laub, MD and
Sujit John, MS
* 2547A Lyon Street, 2nd Floor, San Francisco, California 94123 (Email: jim{at}jbjmd.com).
A recent study in JACC (1) concludes that diastolic function is improved in individuals on long-term calorie restriction (CR) compared to those eating a "Western diet." We would like to point out that other studies demonstrate a correlation between diastolic dysfunction and body mass index (BMI) as an independent factor. In the study by Fontana et al. (1), control subjects eating a Western diet had an average BMI of 27 kg/m2; the CR adherents had a BMI of 19.7 kg/m2. Mortality and morbidity rise significantly above a BMI of 22 kg/m2, and a BMI of 25 kg/m2 is (generously) considered by U.S. Department of Agriculture panelists as the upper limit of normal weight. Therefore, a BMI of 27 kg/m2 is well within the category of overweight. An average male height 5 ft 9 inches with a BMI of 20 kg/m2 weighs 135 lbs. If his BMI is 27 kg/m2, he weighs 35% more at 182 lbs, a 47-lb difference!
In a study of the effect of isolated obesity on diastolic function Pascual et al. (2), state: "Subclinical left ventricular diastolic dysfunction is present in all grades of isolated obesity, correlates with BMI, and is associated with increased systolic function in the early stages of obesity." In that study, a BMI between 25 and 29.9 kg/m2 was classed as "slight obesity." Another study (3) states: "Diastolic function was negatively correlated with age, BMI, systolic blood pressure, diastolic blood pressure and left ventricular mass index."
In addition, control subjects had 26% body fat, and the CR subjects had 9.3%. Obesity is known to raise tumor necrosis factor-alpha and other pro-inflammatory cytokines (4). Long-term inflammatory effects may change ventricular elasticity, but the observed difference may be due more to the large difference in body fat and BMI than to the CR versus Western diets. It is probable that the difference in diastolic function attributed to CR is at least partly due to the secondary effect of being thin, and not the direct result of the CR diet.
Finally, the small number of adherents to a CR life-style speaks to the difficulty in depriving oneself every day of preferred type and amounts of food. We hypothesize (5) that alternate-day calorie restriction, in which one eats less and more than needed to maintain body weight on alternating days, will provide the same health benefits as daily CR; it is a much more agreeable way of living, and it appears to have a profound effect on cardiac function (6).
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References
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- Meyer TE, Kovacs SJ, Ehsani AA, Klein S, Holloszy JO, Fontana L. Long-term caloric restriction ameliorates the decline in diastolic function in humans J Am Coll Cardiol 2006;47:398-402.[Abstract/Free Full Text]
- Pascual M, Pascual DA, Soria F, et al. Effects of isolated obesity on systolic and diastolic left ventricular function Heart 2003;89:1152-1156.[Abstract/Free Full Text]
- Masliza M, Daud SM, Khalid Y. Assessment of diastolic function in newly diagnosed hypertensives Ann Acad Med Singapore 2005;34:684-685.[ISI][Medline]
- Norman RA, Bogardus C, Ravussin E. Linkage between obesity and a marker near the tumor necrosis factor-alpha locus in Pima Indians J Clin Invest 1995;96:158-162.[ISI][Medline]
- Johnson JB, Laub DR, John S. The effect on health of alternate day calorie restrictioneating less and more than needed on alternate days prolongs life. Med Hypotheses 2006;67:209-211.[CrossRef][Medline]
- Vallejo EA. La dieta de hambre a días alternos en la alimentación de los viejos Rev Clin Esp 1956;63:25-27.[Medline]
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