1994;14;1751-1760 Arterioscler Thromb Vasc Biol AH Lichtenstein ...

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Lichtenstein et al Low-Fat Diet, Weight Loss, and Plasma Lipids 1755
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FIQ 1. Une plots of Individual plasma lipid concentrations at
the end of each diet phase. See "Methods" for definitions of
diets. LDL indicates low-density lipoprotein; HDL, high-density
lipoprotein.
and Fig 2). Postprandial plasma cholesterol and non-
HDL-C concentrations were not significantly different
from fasting values. In contrast, HDL-C concentrations
consistently exhibited a postprandial fall of 5% to 7%,
which was significantly different from fasting levels over
all the diet phases.
Mean postprandial plasma triglyceride concentrations
(at 5-, 8-, and 10-hour time points) were approximately
twofold higher than fasting values and were
statistically different from fasting values for all diet
phases. By 24 hours plasma triglyceride concentrations
were statistically indistinguishable from the initial fasting
values regardless of dietary treatment.
The differences observed among diets with respect to
postprandial total cholesterol, non-HDL-C, HDL-C,
and triglyceride concentrations were similar to those
observed in the fasting state. Postprandial total cholesterol
concentrations were from lowest to highest when
the subjects consumed the low-fat (j, energy), reducedfat,
low-fat (-» energy), and baseline diets. In general,
non-HDL-C concentrations were lowest when the subjects
consumed the low-fat (| energy) and reduced-fat
diets and highest when they consumed the low-fat
(-> energy) and baseline diets. HDL-C concentrations
were from lowest to highest when the subjects consumed
the low-fat (—» energy), low-fat (j energy), reduced
fat, and baseline diets. Postprandial triglyceride
concentrations were significantly higher at the end of
the low-fat (-» energy) diet than at the end of any of the
other diet periods.
The study subjects continued to consume the low-fat
(| energy) diet for an additional 5 weeks (Table 5).
Although there was a persistent loss of body weight,
albeit at a somewhat slower rate (0.62±0.47 versus
0.43±0.43 per week, first and second diet periods,
respectively), the greatest effect of weight loss on
plasma lipid and apolipoprotein concentrations occurred
after the first 5 weeks of the fourth study period.
Plasma lipid and apolipoprotein concentrations remained
remarkably stable during the second 5-week
period of the low-fat (J. energy) phase.
Discussion
Impressive observations have been made with respect
to the benefits of extremely low-fat diets on plasma lipid
concentrations and regression of atherosclerotic
plaque. 6 ' 7 ' 58 Populations that normally consume low-fat
diets are generally reported to have lower plasma lipid
concentrations and rates of coronary heart disease than
those consuming higher fat diets. 59 In such populations
caloric intake tends to be lower and fiber intake higher
than in societies consuming higher fat diets, and obesity
is generally not cited as a major public health problem.
5961 In general, the consumption of ad libitum
quantities of low-fat diets relative to higher fat diets
on an experimental basis is accompanied by weight
loss. 45 ' 46 - 6268 Increasing the fat intake of people who
habitually consume a low-fat diet has been reported to
result in weight gain and adverse effects on plasma
lipid concentrations. 69 The results of a recent metaanarysis
of studies assessing the relation between
weight change and plasma lipid levels concluded that
weight loss is associated with an improvement of
plasma lipid profiles. 70
Taking these observations into consideration, we
investigated the effects of reduced-fat and low-fat
diets with and without weight loss on plasma lipid,
lipoprotein, and apolipoprotein concentrations. Middle-aged
and elderly female and male subjects with
plasma LDL-C concentrations that indicated the need
for dietary modification were targeted, since this is the
group for which recommendations to reduce dietary
fat content are frequently made. (Although body mass
index was not a screening criterion, the group of
subjects participating in the study, qualifying on the
basis of having LDL-C levels above 130 mg/dL, had a
somewhat elevated mean body mass index [27.0±4.5]).
We do not have anthropometric measures of the study
subjects, and differences in body fat distribution could
have modified the effect of weight loss on their plasma
lipid levels. Given that limitation, the results of the
investigation suggest, relative to a baseline diet, that
when body weight was maintained, reducing the total
and saturated fat content of the diet in accordance
with the current NCEP step 2 guidelines resulted in a
significant decrease in total cholesterol, LDL-C, and
HDL-C concentrations. Further reducing the total fat
content of the diet under the same conditions also
resulted in decreased concentrations of total cholesterol,
LDL-C, and HDL-C, although the reductions in
total cholesterol and LDL-C were less dramatic and
the decrease in HDL-C greater than when the subjects
consumed the reduced-fat diet. Accompanying these
changes was a striking increase in plasma triglycerides
and VLDL cholesterol concentrations. The end result
was a less favorable plasma lipid profile with respect to
cardiovascular risk. Allowing the subjects to decrease
their caloric intake while maintaining the macronutri-
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