NUTRITION IN SPORT

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.