Hunger and Shopping: Studies Provide Warnings, Advice

Health Letter, August 2014

By Sidney M. Wolfe, M.D.

Everyone agrees that if you are hungry and food is available, eating is the most common response — even better if it is actually mealtime. But what do hunger and shopping have to do with one another? If you guessed that your degree of hunger when you shop may influence what you buy, you are quite right.

Consider the following question: Do you consciously arrange the hour at which you go shopping based on either how hungry you think you will be or, more quantitatively, the relationship of the last time you ate to your planned shopping time? Most of us would probably say, “Not me. That decision depends much more on other factors.”

But if you are interested — for yourself and your family — in eating a healthier diet and maintaining weight or, possibly, trying to lose weight, clear evidence linking hunger and shopping may influence how you time your shopping trips. Not that all common-sense judgments like this need to be tested for their validity, but in this case, it might just help to look at the evidence.

Recent studies on hunger and shopping choices

The most recent and relevant study, published in June 2013 in the Journal of the American Medical Association (JAMA) Internal Medicine, evaluated the effect of the length of time between eating and shopping, comparing the grocery shopping choices of participants from 1 p.m. to 4 p.m., when they were more likely to be full, with the choices of participants shopping from 4 p.m. to 7 p.m., higher-hunger hours based on the greater length of time since lunch.[1]

The difference in high-calorie food purchases between the two groups was not significant. However, the 4 p.m. to 7 p.m. shoppers were significantly less likely to purchase healthy, low-calorie foods than those shopping between 1 p.m. and 4 p.m. As a result of this difference, the ratio of low-calorie to high-calorie foods purchased during the after-lunch hours was much greater than that of the hungrier shoppers.

In an accompanying editorial, JAMA Internal Medicine editor Dr. Rita Redberg stated that “all diet guides include the advice to never go grocery shopping when you are hungry,’’ but the authors of this important study “offer scientific support for this common sense advice in their study of grocery store purchases after short-term fasts.”[2]

A study in 2012 by the same authors had shown that following a longer, 18-hour fast, the initial food choices of fasting study participants — compared to those of nonfasters — comprised both a significantly increased intake of high-calorie foods such as carbohydrates and cheese and lower consumption of higher-nutrient, low-calorie food (vegetables).

Similar to the 2013 study, this study also showed a significantly greater ratio of high-calorie to low-calorie foods chosen in fasters compared to nonfasters, but after this longer fast, the choices by fasters included more high-calorie foods as well as fewer lower-calorie foods.[3]

How to shop more smartly, healthfully

What altered plan of action might you follow based on this newer experimental evidence that reinforces the common-sense idea that your degree of hunger when you shop may influence what you buy?

The simple answer can be found in the title of Redberg’s editorial: “Snack (Healthily) Before Shopping.”

In other words, rather than grocery shop after a period of fasting for as many as four to seven hours, just before you leave for the store, have a low-calorie, high-nutrient snack — such as a fruit or vegetable, or low-fat milk or yogurt — sufficient to lessen your hunger and help you make healthier shopping decisions.

Try it, and see how your shopping habits change.


References

[1] Tal A, Wansink B. Fattening Fasting: Hungry Grocery Shoppers Buy More Calories, Not More Food. JAMA Intern Med. June 24, 2013;173(12):1146-8.

[2] Redberg R. Snack (Healthily) Before Shopping. JAMA Intern Med. 2013 Jun 24;173(12):1148.

[3] Wansink B, Tal A, Shimizu M. First foods most: after 18-hour fast, people drawn to starches first and vegetables last. Arch Intern Med. June 25, 2012;172(12):961-3.