168 Obesity
transportation, and used movement sensors on chairs. Research has also
used the doubly labeled water method. Using this method Schulz and
Schoeller (1994) reported high correlations between percentage body fat
and energy expenditure. Research has also explored links between activity
and body weight with a focus on daily stair climbing, which is recommended
as a simple and cost-free way of incorporating exercise into our lives. To
assess the impact of stair climbing, Shenassa et al. (2008) explored the rela-
tionship between BMI and floor of residence in nearly 3,000 normal-weight
adult across eight European cities. The results showed that for men, living
on a higher floor was associated with lower BMI. This association was not,
however, found for women. The authors concluded that daily stair climb-
ing may reduce weight and therefore should be encouraged. Why the associa-
tion was not there for women is unclear. However, whether reduced exercise
is a cause or a consequence of obesity remains unclear. It is possible that
the obese exercise less due to factors such as embarrassment and stigma
and that exercise plays a part in the maintenance of obesity but not in its
cause. For example, in a large cross-sectional study of over 16,000 adults
in Australia, overweight perception was found to be a strong barrier to
physical activity (Atlantis, Barnes, and Ball, 2008).
What effect does exercise have on food intake?
The relationship between exercise and food intake is complex, with research
suggesting that exercise may increase, decrease, or have no effect on eat-
ing behavior. For example, a study of middle-aged male joggers who ran
approximately 65 km per week suggested that increased calorie intake was
related to increased exercise, with the joggers eating more than the sedentary
control group (Blair et al., 1981). In contrast, another study of military
cadets reported that decreased food intake was related to increased exercise
(Edholm et al., 1955). A review of the literature in 1997 by King, Blundell,
and Tremblay concluded that there is no clear evidence for a relationship
between energy expenditure and energy intake. However, research does
indicate that brisk walking can reduce craving for chocolate (Taylor and
Oliver, 2009).
What effect does exercise have on energy expenditure?
Exercise burns up calories. For example, ten minutes of sleeping uses up
to 16 kcals, standing for 10 minutes uses 19 kcals, running uses 142 kcals,
walking downstairs uses 88 kcals, and walking upstairs uses 229 kcals
(Brownell, 1989). In addition, the amount of calories used increases with