Dietary Supplements for Improving Body Composition and Reducing Body Weight

Changing Body Composition:
Nutrient Partitioning
Substances that fall into the nutrient partitioning category
are hypothesized to work by changing either fat or carbohydrate
metabolism, thus increasing lean body mass and
reducing body fat (see Table 3). Only calcium, conjugated
linoleic acid, and chromium picolinate are discussed here.
Calcium
Higher calcium (Ca) intakes, through supplements or
dairy consumption, are associated with lower body weight
or decreased weight gain (Major et al., 2008). The specific
mechanisms by which Ca/dairy intake may play a role in
regulating body weight are still unknown, but a number
have been proposed:

2006). Unfortunately, research in this area has been
equivocal. Some researchers find that both supplemental
and dairy Ca increase fat oxidation (Melanson et al.,
2003), while others find this effect only with Ca supplements
(Teegarden et al., 2008). White et al. found no acute
effects of dairy Ca intake on fat oxidation during exercise.
Conjugated Linoleic Acid
Conjugated linoleic acid is an isomer of linoleic acid,
one of two essential fatty acids required in the diet. It
is hypothesized that CLA, primarily the cis-9, trans-11,
trans-10, and cis-12 isomers, can increase lean-tissue
mass and decrease body fat based on extensive animal
research (Bhattacharya, Banu, Rahman, Causey, & Fernandes,
2006; Churruca, Fernández-Quintela, & Portillo,
2009; Li, Huang, & Xie, 2008). Research in humans has
not produced the dramatic results observed in animals.
Extensive reviews and two meta-analyses have examined
the effect of CLA supplementation on fat loss or weight
regain after a weight-loss program and report either no
or moderate outcomes. One meta-analysis found a small,
but significant, decrease in fat mass (0.05 kg/week) with
3.2 g/day of CLA over 6–24 months (Whigham, Watras,
& Schoeller, 2007). Conversely, a second meta-analysis
found no significant difference in either body weight or
fat mass in CLA users (3.4 g/day for 1year) compared
with a placebo group (Larsen, Toubro, & Astrup, 2003).
A review by Li et al. reports that most studies fail to
show a decrease in body weight after supplementing
with CLA (0.7–6.8 g/day), while seven studies showed
small changes in fat mass. Finally, a recent review including
RCTs using CLA alone found little or no change
in body weight with CLA supplementation (3.4–6.8 g/
day for 4weeks to 24 months; Egras, Hamilton, Lenz, &
Monaghan, 2011).
Research published after these meta-analyses continues
to show equivocal results. Norris et al. (2009)
reported that CLA contributed to a small decrease in
weight (~1 kg) in obese postmenopausal women, while
Diaz, Watkins, Li, Anderson, and Campbell (2008) found
no effect of CLA (1.8 g/day) on body composition or
weight in overweight women on an energy-reduced diet
(–500 kcal/day) plus 30 min exercise 5 days/week for 3
months. Conversely, two recent studies have shown small
improvements in body composition (~1.2 kg gain in lean
tissue vs. controls) in normal-weight young (Pinkoski
et al., 2006) and older (Tarnopolsky et al., 2007) adults
using CLA (5–6 g/day for 7–24 weeks) and participating
in resistance exercise. Finally, there appears to be
no effect of CLA on exercise performance (Campbell &
Kreider, 2008).
The inconsistency between human clinical trials and
animal studies may be due to differences in age, gender,
and CLA dose and isomer form (Li et al. 2008; Plourde,
Jew, Cunnane, & Jones, 2008). Most animal studies are
done in young growing animals, while the human research
is done in adults, primarily overweight women. Humanresearch
studies typically feed a single CLA isomer.

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