sugar. That’s because the carbs or starches present in potatoes act like sugar. The
rapid rise in blood sugar you experience after eating a baked potato is the same
as you’d experience after eating a doughnut! A potato has fewer calories, of
course, but it leads to a high insulin level, which can make you hungry.
Most versions of the glycemic index assign sugar with the number 100 and
compare other foods on an ascending or descending scale from that point (Fig.
4.4). Foods that are low on the glycemic index are usually high in fiber and have
been shown to promote satiety by allowing the gradual release of sugar into the
bloodstream (and they don’t make you feel hungry) (Fig. 4.5). On the other
hand, foods that are high on the glycemic index, like potatoes, lack fiber and
have been shown to promote weight gain by increasing insulin secretion.
Unless the consumer understands the differences in carbs (the glycemic index
offers an easy way to do this), he or she will not understand that a low-fat diet
increases the risk of heart disease, obesity, and diabetes. But portion size counts
too. Americans are eating more high-glycemic foods and taking in very little fat
to delay the absorption of sugar into the bloodstream. In other words, eating
some mashed potatoes with some sour cream once in a while may not harm you,
but if you eat a lot of mashed potatoes with no fat at all and don’t Figure 4.4:
Glycemic Index of Various Foods
burn the sugar, you are guaranteed to gain weight. Why? You’ll produce too
much insulin and inhibit glucagon, the hormone that melts the fat.