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Peanut butter calories, and the spoon problem

Peanut butter is 598 calories per 100 g — the densest thing in most kitchens that is not straight oil. USDA puts two tablespoons at 32 g, or 191 calories. The trouble is that a tablespoon of peanut butter is a matter of opinion.

Per 100 g, smooth, with salt

Volume is the wrong instrument here

Most foods forgive being measured by spoon. This one does not, for two reasons: it is sticky enough that a "level" spoon is a judgement call, and it is dense enough that being wrong is expensive. At 5.98 calories per gram, a 10 g overshoot is 60 calories. Do that twice a day and it is over 800 calories a week that never got logged.

Compare the arithmetic to something forgiving: 10 g of extra broccoli is 3 calories. Peanut butter is twenty times as unforgiving per gram of error.

USDA’s tablespoon is level.

What is actually in it

Per 100 g: 51.4 g fat, 22.3 g carbohydrate, 22.2 g protein. It gets talked about as a protein food, and 22 g per 100 g is real — but so is the fact that 77% of its calories come from fat. As a protein source per calorie it is roughly a fifth as efficient as Greek yogurt. Eat it because it is good, not because it is an efficient way to hit a protein target.

Natural versus regular

The figures here are for standard smooth peanut butter with salt. Natural versions — peanuts and salt, oil separating on top — land within a few calories per 100 g, because the stabilizers and small amount of added sugar in regular peanut butter do not move the total much. The choice is about ingredients and texture, not calories. Reduced-fat versions genuinely are lower, and usually replace the fat with carbohydrate.

Source: USDA FoodData Central, SR Legacy release 2018-04. Figures are per 100 g as published; serving weights are USDA’s own. Records used: Peanut butter, smooth style, with salt (Includes foods for USDA's Food Distribution Program) (FDC 174266).

Common questions

USDA puts two tablespoons at 32 g, so one level tablespoon is 16 g and about 96 calories. A heaped spoon can easily be 24 g, or 143 calories.

It contains 22.2 g per 100 g, which is substantial, but 77% of its calories come from fat. Per calorie it is a far less efficient protein source than yogurt, chicken or eggs.

Barely. Standard and natural peanut butters land within a few calories per 100 g of each other. Reduced-fat versions are genuinely lower, usually with more carbohydrate.

Because it is 5.98 calories per gram, so a 10 g misjudgement is 60 calories. Few other foods punish an inaccurate spoon that hard.

Compare it with

All twenty-four are on the food macros index.