How Do You Change Lifelong Eating Habits?
A recent study published in the Journal of the American Dietetic Association documents one way to change eating habits: exchange lists.
Your basic exhange list is a list of recommended foods, with serving sizes and frequencies. For example, I could give you note recommending you eat three pieces of fruit, four 1-cup servings of vegetables, and two tablespoons of healthy oils daily. Then I give you a list fruits, vegetables, and oils from which to choose. You decide which fruits to eat from the list, just be sure to eat three servings daily. One fruit is as good as the other: they are exchangeable. You check off your intake as you go through the day. People with diabetes have used exchange lists for years.
Researchers with the University of Michigan Health System plan to test a Mediterranean-style diet for breast cancer prevention. Several previous observational studies have associated the Mediterranean diet with lower rates of breast cancer (along with lower rates of colon, uterus, and prostate cancer). The researchers wondered how to get women to change their diet in the direction of a Greek-Mediterranean diet. They devised an exchange list to promote high intake of monounsaturated fats and fruits and vegetables. Would women follow it?
Methodology
Sixty-nine women, ages 25 to 59, were enrolled to either continue their usual diet or to follow a six-month intervention diet designed to:
decrease usual fat intakes by about half and to replace those fats with olive oil and other high–monounsaturated fatty acid foods; increase fruit and vegetable intakes to 7 to 9 servings/day, depending on energy intake; and consume at least one serving per day each of culinary herbs and allium vegetables.
Allium vegetables include onions, leeks, chives, garlic, and shallots.
Dietitians designed a Mediterranean diet exchange list, specified exchange goals, and provided individualized telephone counseling. Counseling was in-person at the start of the study and three months later.
Here’s a quote from the University of Michigan Health System news release:
In this new study, specific suggestions in the exchange list included:
- 8-10 servings (or exchanges) each day of high monounsaturated fatty acid (MUFA), such as olive or hazelnut oil, avocado and macadamia nuts
- Limits on fats that are low in MUFA, such as corn oil, margarine, tahini, pine nuts and sesame seeds.
- One or more servings a day of dark green vegetables, such as broccoli, peas and spinach
- At least one exchange per day of garlic, onions and leeks
- One tablespoon or more per day of green herbs, such as basil, cilantro, peppermint and sage
- One or more servings a day of red vegetables, such as tomatoes, tomato sauce and salsa
- One or more servings a day of yellow or orange vegetables, such as carrots, red bell peppers and pumpkin
- One or more servings a day of other vegetables, such as artichokes, cucumber, green beans and sugar snap peas
- One or more servings a day of vitamin C fruits, such as oranges, mangoes and strawberries
- One or more servings a day of other fruits, such as apples, bananas and grapes
Results
Compared to the non-intervention (control) group, the Mediterranean group:
- increased dietary monounsaturated fat by 48% (with no change in total fat intake)
- increased fruit and vegetable intake from 4 to 8.6 servings a day
Researchers’ Conclusions
Results demonstrated that counseling using the Mediterranean exchange list was effective for large dietary changes relative to the nonintervention group.
My Comments
I can’t wait to see the larger prospective study regarding breast cancer reduction with a Greek-Mediterranean diet. But it will take years. And the dietary effects likely are cumulative over years of eating, not just six months. This is a start.
We have seen with weight-loss diets that people typically return to their old ways of eating six to twelve months after making a change. That’s why it’s so difficult to demonstrate irrefutably that one diet is healthier than another. How do you get 10,000 people to make major dietary changes and sustain them for 10-20 years, and another similar group of 10,000 people to make no changes? [After 20 years, you compare the health status of both groups.]
I suppose we could study prisoners serving life terms. Hmmm . . .
Many of us can’t wait 10 or 20 years for study results. We have to make food decisions now, based on the best available data.
My Advanced Mediterranean Diet uses an exchange list system - Daily Logs & and Grocery Shopping List - to approximate the Mediterranean diet. People seem to like the flexibility.
Steve Parker, M.D.
References:
Djuric, Zora, et al. Design of a Mediterranean Exchange List Diet Implemented by Telephone Counseling. Journal of the American Dietetic Association, 108 (2008): 2,059-2,065.
University of Michigan Health System news release, “Women double fruit, veggie intake with switch to Mediterranean diet,” December 17, 2008.
March 11th, 2009 at 2:31 pm
I can’t answer your question as to how, but in my experience, the why often turns out to be a serious scare from a debilitating medical event. The interesting thing is that people who were absolutely sure they could never change, do it. The good news is that we are all able to make choices if we really want to.
March 11th, 2009 at 3:59 pm
It seems so often that people will not change until continuing on in their old ways is too painful. Dr J, you mention the pain of a scary medical event.
You and I both see too many people with medical events that could have been prevented or ameliorated by better choices of diet and physical activity 10-20 years earlier. But the horse is out of the barn….
It’s also true I could make all the healthy choices for years and still get run over by a beer truck tomorrow.