On Nutrition by Ed Blonz

Doing the Math on Fat

DEAR DR. BLONZ: There is an inconsistency I hope you will “weigh in” on. If a pound is the equivalent of 454 grams, and there are nine calories per gram of fat, this would suggest that a pound of body fat will have 4,086 calories. Please explain the common referral to a pound of fat having only 3,500 calories. The math does not add up. -- D.L., East Orange, New Jersey

DEAR D.L.: Fat is our most calorie-dense substance, and it is capable of providing an energy equivalent to nine calories per gram. It is utilized as the primary form of energy storage because humans, like other animals, need to be mobile. If our energy was stored as carbohydrate or protein, the human body would take up over twice the space it does now. Think what size pants you’d need then!

There are 454 grams in a pound, as you correctly point out. So how do we come up with 3,500 calories in a pound, when 454 x 9 = 4,086 calories? The answer rests with the fact that body fat is not pure fat. The adipose tissue that houses the stored fat contains a small amount of water and some structural material, accounting for close to 15 percent of tissue weight. It is this nonfat portion that helps explain why a pound of body fat is said to contain approximately 3,500 calories worth of stored energy.

DEAR DR. BLONZ: I enjoy almonds in many forms, including almond butter, but have been wondering if I get the same nutritional benefits from roasted and unroasted almonds. And what about fat-roasted versus dry-roasted nuts? -- P.W., via email

DEAR P.W.: The roasting of almonds, peanuts or other foods helps to bring about flavor-enhancing chemical reactions in the food. With nuts, this can be accomplished with or without oils, which can impart their own flavor notes. Dry roasting requires specially designed ovens that use heated air to do the cooking. The processor can then add salt, paprika or other flavorings as desired.

Oil roasting adds only about a gram of fat per 1-cup serving. This small difference is explained by the fact that half the weight of the nut -- and more than 70 percent of its calories -- comes from the fats already present. The addition of flavorings, depending on the type used, can affect the level. Honey-roasted nuts, for example, contain less fat per serving because some of the weight is taken up by the sugary coating.

Roasting, being a high-heat process, does destroy some of the heat-sensitive nutrients, which include thiamine and vitamin C. But don’t view this as the deciding factor, as almonds are not the go-to food for these nutrients anyway. Other nutrients are unaffected. Check the complete list of nutrients for almonds at the USDA database: ndb.nal.usda.gov/ndb.

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.