Biomedical Engineering Reference
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Fig. 6 Adipose cell-size distribution fit with Model 2: Here we show both the adipose cell-size
distribution from experimental data (in pink for the right side and light blue for the left side) and
the corresponding fit using Model 2 (red
and dark blue, respectively)
should agree with the fat mass change predicted by body composition models. This
raises a puzzle. Parameters describing adipose cell size distributions are correlated
with measures of insulin resistance, so changes in fat mass computed from adipose
tissue dynamics will depend on insulin resistance through this correlation with
initial adipose cell size distributions [
12
,
26
,
35
,
36
]. However, the body com-
position model [
33
] depends on BMI, gender, age and physical activity level but
not on insulin sensitivity. It must follow that parameters determining the dynamics
of adipose cell size distributions depend on insulin resistance in a manner that
compensates
for
the
insulin
resistance
dependence
of
the
initial
cell-size
distributions.
Adipocyte cell-size distribution and physiology data from 28 individuals [
12
]
was separated into six subgroups based on insulin resistance/sensitivity (IR/IS)
and/or gender (F/M). Using this data, a body composition model was evolved with
isocaloric, weight maintenance diets with different carbohydrate composition
0-100 %, for a period of two weeks. The adipose tissue dynamics model was
simplified to exclude effects from increases in cell number. As the time period
under consideration is short (two weeks) and the weight change is not dramatic due
to an isocaloric diet, this simplification is justified. The majority of the fat that is
stored in the fat cells is in larger fat cells as evident in a volume-weighted adipose
cell size distribution (Fig.
7
). The volume weighted adipose cell size distribution
predominantly consists of the cell sizes that are in the Gaussian component of the
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