One of the best ways to keep your weight in line is a principle as old as home economics itself — shop for groceries with a list. Going to the store with a list made in advance and in hand saves time and money, and makes it likelier you'll eat better — at least if you stick to your list.

Grocery stores are carefully designed to tempt you to make impulse purchases. Why do you think they put snacks and soft drinks at the checkout, and sugary cereals on the ends of aisles?

Not only does this kind of marketing encourage poor food choices, it also plays havoc with your budget.

Those who regularly shopped from a list had healthier diets, and their BMI was about one point lower than those who didn’t regularly use a grocery list.

A study of at-risk residents in Pittsburgh found that those who regularly shopped with a grocery list made higher quality food choices and they weighed less.

Most of the 1300 people in the study were obese or overweight. They lived in primarily African American communities and reported a household income of less than $20,000 per year. Only 33 percent were employed.

Their neighborhood was a food desert, with limited access to healthy food.

About one-third of the participants said they “always” used a grocery list when shopping. Not only did researchers find that those who did had healthier diets, their BMI was about one point lower than those who didn’t regularly use a grocery list.

Plan several days’ worth of nutritious meals and make a grocery list around them.

The study wasn’t designed to show that grocery lists lead to better health or lower weight, but it does point to a link between the two. The shopper writing down their selections before grocery shopping may have been doing other things to eat healthier or maintain a lower weight.

Planning meals and making a grocery list is not just for people living in a food desert, but for everyone who is trying to eat healthy and control their weight.

You only need to spend a few minutes once a week to reap the benefits. Plan several days’ worth of nutritious meals and make a grocery list around them. This reduces the amount of time you spend shopping for food, and if you stick to your list, it saves money and helps you avoid high-calorie impulse purchases. It will also help you follow through with the healthy meals you planned.

The study is published in the Journal of Nutrition Education and Behavior.