How the economy affects your diet and your weight.

Cutting back on spending may not mean cutting down on calories.

The more "energy dense" a food is — i.e., the more calories it contains per unit weight — the less it costs per calorie. For instance, the lowest-cost vegetables, per calorie, are potatoes; cheese costs less per calorie than fresh spinach; and the sugar in fresh raspberries is 100 times more expensive per calorie than ordinary table sugar. (Source: 2004 University of Washington study published in Nutrition Today.)

Not surprisingly, as the prices of foods go down, the purchases of those foods go up, and vice versa. Between 2004 and 2006, the prices of very-high-calorie foods dropped by an average of 1.8%, while the prices of very-low-calorie foods went up by an average of 19.5%. (Source: 2007 University of Washington study published in the Journal of the American Dietetic Assn.)

So, by spending less on food, we could end up gaining weight. And there's not a lot of margin for error in that respect.

Here's where we stand now:

More than 1 in 3 adult Americans are obese — 33.3% of men and 35.3% of women. The rates have more than doubled since the late 1970s.

Since that time, children have grown increasingly overweight, with rates rising from 5% to 13.9% for 2- to 5-year-olds, from 6.5% to 18.8% for 6- to 11-year olds and from 5% to 17.4% for 12- to 19-year olds.

Obesity is a risk factor for cardiovascular disease, some kinds of cancer and Type 2 diabetes. (Source: Centers for Disease Control and Prevention.)

Spending on food is down by $56 billion this January compared with January 2008, according to the Commerce Department. That could mean we're eating less food, which might not be a bad idea for some of us. Then again, we could just be eating less expensive food.

A September 2008 survey found that Americans had made these changes in their eating habits because of the bad economy:

* 43% were eating out less often than they used to.

* 39% were eating at less expensive restaurants.

* 35% were eating at fast-food restaurants less often.

* 35% had started packing a lunch for work.

* 32% had started eating more leftovers.

* 32% had started using coupons.

* 32% were buying more store-label groceries instead of name brands.

* 30% were ordering less food when they went out to eat.

* 22% were drinking tap water instead of soda and noncarbonated drinks.

* Less than 10% had switched to a less expensive brand of alcohol or beer.

(Source: September 2008 Consumer Spending Behavior Study conducted by Booz & Co.)

-- Karen Ravn