From: ingrid@wubios.wustl.edu (Ingrid Borecki)
Newsgroups: sci.med
Subject: Re: Is cycle dieting safe?
Date: 17 Apr 92 20:08:59 GMT
Article-I.D.: wubios.1992Apr17.200859.1155
Organization: Division of Biostatistics, WUMS, St. Louis, MO

In article <14392@pitt.UUCP> geb@dsl.pitt.edu (gordon e. banks) writes:
>
>We've seen it claimed by Chuch Forsberg (Adiposity 101) and others
>that dieting is dangerous, 

Firstly, I don't believe dieting is dangerous.

>and more specifically, leads to reduced
>lean body mass and metabolism.  

It does, at least in the course of dieting (sustained negative energy balance)
and loss of lean body mass is more likely if the diet is not properly
balanced and exercise to foster growth of lean body mass does not accompany
the process.  These effects cease after the individual enters the
"maintenance" phase.

>Rena Wing's latest paper in Am J
>Clin Nutr (55:641) has contrary evidence.  In a study (in which I
>was a participant) of 202 obese people, subjects were separated into
>quartiles with respect to cycle dieting.  Those in the 4th quartile,
>for example, had cycled an average of more than 8 times with a 
>total cumulative weight loss/gain of more than 117 kg (men) and
>14 times with weight loss/gain of more than 138 kg (women).
>In the first quartile, she had those who had never cycled,
>for the men, or only once for the women, with a loss/gain of 15 kg or
>less.  

Need some clarification, please.  Now these subjects were classfied
into quartiles on the basis of their "degree of cycling" by some
operational definition, but what were these subjects doing now?
Were they all maintaining their healthy post-weight-loss weight?
Were any of the subjects back to old tricks and had regained
their previous weight loss?  That is, at which part of the
cycle were these subjects:  up, down, or anywhere in between?
If it is a mixture of all these, it would be quite hard to
interpret the results of the study . . . 

>Measurements of fatness, lean body mass, blood pressure,
>cholesterol, percentage of diet from fat, and other parameters
>showed no significant differences between those who cycled and
>those who didn't for either sex.  Those differences that there
>were, although not significant, were all in the opposite direction
>from the claims Chuck made (i.e. the cyclers had lower fat percentage
>than those who never dieted, and higher lean body mass).  

Might be expected, depending on the current energy intake and expenditure
balance being achieved for each subject.

>So, perhaps in mice, dieting is just going to make them fatter,
>but in humans, this is not the case.  Gallstones remain the
>only complication of cycle dieting yet discovered.

Keys et al. (1950.  "The Biology of Human Starvation", Vols 1 & 2.
University of Minnesota Press, Minneapolis, pp 1385) observed in
clinical studies that healthy male volunteers who lost weight by
food restriction and then regained it were fatter after regain than
at the beginning of their weight reduction.  Over time, the body
weight and composition returned to preweight reduction levels.
In another study of the loss-regain cycle, Drenick et al (1964;
JAMA 187:100-105) and Johnson and Drenick (1977; Arch Intern Med
137:1381-1382) placed approximately 200 obese men on total fasts,
some for more than 2 months and the rest for 3 to 8 weeks.
After refeeding, the men regained their lost weight, often
exceeding their original weight.  80% developed diabetes;
1/2 of these cases were severe. 

Data from one of the largest and longstanding epidemiological studies
(with longitudnal data, I might add)
of cardiovascular disease, the Framingham study, suggests that a
30% increase in coronary heart disease (CHD) was associated with a
10% weight gain, and a 20% decrease in CHD was associated with a
10% weight loss (Ashley and Kannel, 1974; J Chron Dis 27:103-114).
Thus, repeated cycles of weight loss and gain might exert a net 
negative effect; however, relatively few attempts have been made
to address this question directly by studying subjects who lose 
and subsequently regain weight.  In another large study, Hamm
et al. (1989; Title:  Large fluctuations in body weight during
young adulthood and 25-yr risk of coronary death in men.  
Am J Epidemiol 129:312-318) found that his gain-and-loss group
had a significantly higher risk of CHD mortality when compared to
the no-weight-change group.  The adjusted relative risk was 1.8.

The question about the health consequences of repeated cycles of
dieting is *far* from solved.  There are few studies that have
addressed this issue thus far, and clearly, to be valid, the
studies should be prospective with adequate controls.  I think
your conclusions way up above, now, are premature and cannot
be stated with the degree of certainty you seem to have.

I think we can also appreciate that there is a difference
between understanding the biology through the scientific
process and how that translates in public recommendations.
(Let's just think about the oat bran thing . . .)
The question is far from solved scientifically; the
recommendation is try to get the fat off and KEEP it off.
-- 
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~|
|            Ingrid Borecki                   |  Washington University |
|       Division of Biostatistics             |  School of Medicine,   |
|        ingrid@wubios.wustl.edu              |  St. Louis, Missouri   |
From: kingsley@hpwrce.HP.COM (Kingsley Morse)
Date: Wed, 8 Apr 1992 15:54:45 GMT
Subject: Class action against FDA
Organization: HP Western Response Center