It's easy to fall into a rut and eat the same meals and snacks day after day. Doing so helps control calories, curbs temptation and takes the stress out of meal planning.
But if you're carrying excess weight, a new study suggests, variety may be the key to weight-loss success - at least when it comes to snacks. What's more, how much you weigh may dictate your need for variety or monotony.
In an earlier study, in 2008, researchers from the University at Buffalo, New York, found that "food reinforcement" - a term used to describe the motivation to eat - decreased in non-obese women who were asked to eat their favourite snack, be it cookies or candy, every day for two weeks straight. Eating the same snack every day reduced its appeal.
Now, in a study published in the August issue of the American Journal of Clinical Nutrition, the same research group tested the responses to sugary or fatty snacks in 31 non-obese and 27 obese women.
Women were classified as obese if their body mass index was greater than 30; non-obese women had a BMI under 30.
In the first part of the study, the women were given a 100-calorie portion of a highly likeable snack and told to eat the same snack every day for two weeks. Snacks were either high-fat, sugary foods (cookies, doughnuts, chocolate bars, ice cream) or high-fat, salty foods (potato chips, corn chips, French fries). A third group of women consumed no snacks.
After completing their assignment, the participants returned to the lab, where they could "work" for their 100-calorie snack by performing tasks on a computer and earning points.
Women repeated the cycle, this time with a 300-calorie snack, which they ate for 14 days in a row and then returned to perform computer tasks.
When the women were tested on the computer, both obese and non-obese women worked equally hard for the 100-calorie snack. But the drive to work for the 300-calorie snack decreased in non-obese women. Their interest in it had declined.
The obese women, however, worked harder to get the 300-calorie snack, even though they said they liked it less than at the beginning of the study. Some reported still wanting the food even though they no longer liked it.
The researchers speculate that brain chemistry is involved: repeated intake of the snack food caused the obese women to want it more, a pattern similar to drug addiction. It's also possible that 300 calories was the optimal dose, so to speak, for reinforcing food intake in obese women, but not those who were non-obese.
These findings suggest that the obese women were not eating out of hunger. Eating the snack fulfilled some other need. (The experiments were run during the lunch period: The women were instructed to eat their normal breakfast and were fed 150 calories right before testing to minimize the effects of hunger on food reinforcement.)
The fact that preference for the food declined among all women after they ate it repeatedly, but the motivation to continue eating it differed by weight status, suggests that limiting your snack option may not be wise, especially if you're obese.
Eating a variety of healthy snacks may curb the drive to eat.
Other research has found that adults experience more cravings during the day after following a monotonous versus a varied diet. Boredom may send dieters on a quest for their favourite foods.
If you're carrying excess weight, perhaps it's what foods you vary - and limit - that matters most. A 2009 study involving 84 children revealed that the impact of variety is more evident for high-calorie foods. Given a variety of nacho chips, potato chips, cookies and chocolate bars, overweight children consumed more calories than leaner kids did.
Participants in the U.S. National Weight Control Registry, a database of more than 5,000 men and women who have lost, on average, 70 pounds and kept the weight off for years, report limiting the variety of high-fat foods and sweets in their efforts to stay trim.
Snacks are an important part of a weight-loss plan. For the vast majority of clients in my private practice, including between-meal snacks staves off hunger and prevents overeating at the end of the day. Snacks boost blood sugar and keep it relatively stable until mealtime.
Healthy snacks should include slowly digested carbohydrate and protein. If you're trying to lose weight, keep snacks to 150 to 200 calories for women and 200 to 250 calories for men.
Try a piece of fruit and a small handful of almonds (250 calories), a 16-ounce non-fat latte (160 calories), a single serving of 1 per cent yogurt and berries (200 calories), instant bean soup (240 calories), raw vegetables and a quarter cup of hummus (180 calories), one apple and one or two tablespoons of peanut butter (175-260 calories) or an energy bar (200 to 250 calories).
Avoid high-glycemic snacks such as refined-cereal bars, pretzels, muffins, bagels, cookies and sugary drinks. They make your blood sugar spike, causing premature hunger.
Bring your snacks to work so you're not temped to hit the vending machine or raid the office candy jar when your energy dips.
But don't eliminate your favourite snacks from your weight-loss plan, whether they are sweet or salty. If you feel deprived, you'll end up craving them and, very likely, overeating to make up for their absence.
And according to this study, if you are obese, making these foods the exception rather than the rule may reduce your motivation to eat them.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.