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A paper has compared the effects of relatively modest
reductions in the
amounts of carbohydrates in the diets of subjects for whom
rather large
amounts of weight was desired to be lost, and for whom
significant reduction
in their caloric intake was required. It appeared to this
observer that the
percentage of recommended saturated fat intake by the lower
carbohydrate
dieters was not achieved. Moreover, the ratio was strongly
shifted in favor
of polyunsaturated and monounsaturated fats, as a percentage
and as absolute
amounts. This may have had beneficial effects, in addition
to the potential
of the lower carbohydrates to have beneficial effects.
Would the difference
in the weight loss, although they were not significant,
requiring the
greater decrease in caloric intake that is usually seen with
lower
carbohydrate diets, reduce or eliminate the significance of
the cardiac risk
factors that were observed? It is true that the study
subjects were obese,
but some CRer initiate CR while still obese. The caloric
intakes appeared
to be relatively low for safe and effective CR, however.

Tracey McLaughlin et al and Gerald Reaven
Effects of moderate variations in macronutrient composition
on weight loss
and reduction in cardiovascular disease risk in obese,
insulin-resistant
adults
Am J Clin Nutr 2006 84: 813-821.


... recent reports questioned the superiority of
low-fat diets. ... We
aimed to ascertain the effects of moderate variations in the
carbohydrate
and fat content of calorie-restricted diets on weight loss
... Fifty-seven
randomly assigned, insulin-resistant, obese persons
completed a 16-wk
calorie-restricted diet with 15% of energy as protein and
either 60% and 25%
or 40% and 45% of energy as carbohydrate and fat,
respectively. ... RESULTS:
Weight loss with 60% or 40% of energy as carbohydrate (5.7
+/- 0.7 or 6.9
+/- 0.7 kg, respectively) did not differ significantly, and
improvement in
insulin sensitivity correlated with the amount of weight
lost (r = 0.50, P <
0.001). Subjects following the diet with 40% of energy as
carbohydrate had
greater reductions in daylong insulin and triacylglycerol (P
< 0.05) and
fasting triacylglycerol (0.53 mm; P = 0.04) concentrations,
greater
increases in HDL-cholesterol concentrations (0.12 mm; P <
0.01) and LDL
particle size (1.82 s; P < 0.05), and a greater decrease in
plasma
E-selectin (5.6 ng/L; P = 0.02) than did subjects following
the diet with
60% of energy as carbohydrate. CONCLUSIONS: In obese,
insulin-resistant
persons, a calorie-restricted diet, moderately lower in
carbohydrate and
higher in unsaturated fat, is as efficacious as the
traditional low-fat diet
in producing weight loss and may be more beneficial in
reducing markers for
cardiovascular disease risk.

.... 2 calorie-restricted diets that differed in
relative fat and
carbohydrate content by only 20% of total calories. ...
required to have a
body mass index ... between 29 and 36, no recent (3 mo)
history of weight
loss, no use of weight loss drugs, and no history of major
organ disease.
... randomly assigned to a 16-wk period of caloric
restriction, during which
time they were advised to consume 1 of 2 diets, each of
which contained 15%
of total calories as protein, 7% as saturated fat, 200 mg
cholesterol/d, and
20 g fiber/d. However, the 2 diets varied in carbohydrate
(40% versus 60% of
energy), monounsaturated and polyunsaturated fat (38% versus
18% of energy),
and total fat (45% versus 25% of energy). .... After the 16
wk of calorie
restriction, a 2-wk period of weight maintenance was
initiated, during which
time participants were instructed about a eucaloric diet
that was based on
their weight at the end of the intervention but with a
macronutrient content
similar to that of the hypocaloric diet. At the end of the
14-d period of
weight maintenance (ie, week 18), all of the baseline
measurements were
repeated. However, in this instance, the daylong
measurements of plasma
glucose and insulin were made in response to the
experimental diets, ie, the
diet with 40% of energy as carbohydrate (the 40%
carbohydrate diet) and that
with 60% of energy as carbohydrate (the 60% carbohydrate
diet). ...

... RESULTS ... Of the 106 obese persons meeting the
general
eligibility criteria, 66 (60%) were insulin resistant as
defined by their
SSPG concentration at baseline ... yielded an initial cohort
of 65 subjects.
Four persons in each experimental group (12% of the total
group) dropped out
before completing the weight-loss period. The baseline
characteristics of
the 57 persons completing the study -- 30 assigned to the
60% carbohydrate
diet and 27 assigned to the 40% carbohydrate diet -- are
shown in Table 1.
It is apparent from that table that the baseline clinical
variables of the 2
groups did not differ significantly. ... Estimates from food
diaries ... in
Table 2, and it appears that the differences between the 2
groups in fat and
carbohydrate intakes may have been slightly less than
intended. ...

[...]

In summary, ... lose comparable amounts of weight when
following
calorie-restricted diets that vary moderately in
carbohydrate and fat
content, and the amount of weight lost is the most important
determinant of
the improvement in insulin sensitivity. ... beneficial
changes associated
with weight loss in terms of lipoprotein metabolism,
postprandial insulin
and triacylglycerol concentrations, and markers of
endothelial function
improved to a greater degree in subjects following the 40%
carbohydrate diet
than in those following a 60% carbohydrate diet. ... we
could not evaluate
the putative benefit of diets that are relatively high in
both fat and
protein. ... because we provided only dietary
recommendations, and not
actual meals, a lack of precise dietary control may have
obscured metabolic
effects ... a calorie-restricted diet that is moderately
greater in
unsaturated fat and lower in carbohydrate resulted in
amounts of weight loss
comparable to those seen with the diet currently recommended
by the ADA,
AHA, and NHLBI and led to perhaps greater reductions in CVD
risk than did
the recommended diet. ...