352 THE CHINA STUDY
average, actually consumed more calories.^3 ,4 Again, this only reinforced
the tumor-promoting effect observed for casein.WHAT WAS THE OVERALL HEALTH OF THE RATS
ON A LOW-PROTEIN DIET?
Many researchers have long assumed that animals fed diets this low in
protein would not be healthy. However, the low-protein animals were
healthier by every indication. They lived longer, were more physically
active, were slimmer and had healthy hair coats at 100 weeks while the
high-protein counterpart rats were all dead. Also, animals consuming
less dietary casein not only ate more calories, but they also burned off
more calories. Low-protein animals consumed more oxygen, which is
required for the burning of these calories, and had higher levels of a spe-
cial tissue called brown adipose tissue,5,6 which is especially effective in
burning off calories. This occurs through a process of "thermogenesis,"
i.e., the expenditure of calories as body heat. This phenomenon had
already been demonstrated many years before.^7 -^11 Low-protein diets en-
hance the burning off of calories, thus leaving less calories for body weight
gain and perhaps also less for tumor growth as well.
WAS PHYSICAL ACTIVITY RELATED TO THE
CONSUMPTION OF THE LOW-PROTEIN DIET?To measure the physical activity of each group of rats, we compared
how much they voluntarily operated an exercise wheel attached to their
cages. A monitor recorded the number of times the animals turned
the exercise wheel. The low-casein animals^12 exercised about twice as
much, when measured over a two-week period! This observation seems
to be very similar to how one feels after eating a high-protein meal: slug-
gish and sleepy. I have heard that a side effect of the protein-drenched
Atkins Diet is fatigue. Have you ever noticed this feeling in yourself
after a high-protein meal?