sparing may contribute indirectly to fat storage
by sparing dietary fat.
Fat balance
Fat balance is not as precisely regulated as either
protein or carbohydrate balance (Flatt 1992).
Figure 35.2 shows that as fat intake increases, the
oxidation of fat does not increase proportion-
ately (Thomas et al. 1992). Thus, acute increases
in fat intake have little influence on fat oxidation.
For example, Jebb et al. (1996) overfed three lean
men by 33% of energy requirements for 12 days.
They found that carbohydrate and protein intake
the overweight athlete 471
200
150
100
50
0
1000
800
600
400
200
0
200
150
100
50
0
–50
0 50 100 150 200
0 50 100 150 200
0 200 400 600 800 1000
Protein intake (g.day–1)
CHO intake (g.day–1)
Fat intake (g.day–1)
(a)
(b)
(c)
Protein oxidation
(g
.day
–1
)
CHO oxidation
(g
.day
–1
)
Fat oxidation
(g
.day
–1
)
Fig. 35.1High-carbohydrate diet: the relationship
between intake and oxidation of (a) protein, (b)
carbohydrate (CHO), and (c) fat for all subjects on day
7 of a high carbohydrate feeding period. —, regression
line for all 21 subjects; - - - , regression line for lean
subjects (); · · · ·, regression line for obese subjects ().
(a) Lean subjects: r=0.79,P<0.01; obese subjects:
r=0.59, n.s. (b) Lean subjects: r=0.74,P<0.01; obese
subjects:r=0.79,P<0.01. (c) Lean subjects: r=0.06,
n.s.; obese subjects: r=–0.08, n.s. From Thomas et al.
(1992), with permission.
500
400
300
200
100
0
300
200
100
0
200
150
100
50
0
0 50 100 150 200
0 100 200 300
0 100 200 300 400 500
Protein intake (g.day–1)
CHO intake (g.day–1)
Fat intake (g.day–1)
(a)
(b)
(c)
Protein oxidation
(g
.day
–1
)
CHO oxidation
(g
.day
–1
)
Fat oxidation
(g
.day
–1
)
Fig. 35.2High-fat diet: the relationship between intake
and oxidation of (a) protein, (b) carbohydrate (CHO),
and (c) fat for all subjects on day 7 of a high fat feeding
period.—, regression line for all 21 subjects; - - - ,
regression line for lean subjects (); · · · ·, regression
line for obese subjects (). (a) Lean subjects: r=0.78,
P<0.01; obese subjects: r=0.74,P<0.02. (b) Lean
subjects:r=0.32, n.s.; obese subjects: r=0.14, n.s.
(c) Lean subjects: r=0.78,P<0.01; obese subjects:
r=0.02, n.s. From Thomas et al. (1992), with
permission.