Researchers? recommendations for a healthy diet
By Kathleen Zelman, MPH, RD, LD
WebMD Weight Loss Clinic - Expert Column
How do we determine just what (and how much) you need to eat to be healthy? The WebMD Weight Loss Clinic plan is based on recommendations of the National Academy of Science?s (NAS) Food and Nutrition Board.
For more than 50 years, the board has been reviewing the latest research findings to determine what should go into a healthy diet. Until very recently, the board issued guidelines called Recommended Daily Allowances (RDAs), based on the levels of various nutrients our bodies need to prevent diseases caused by deficiencies.
But as researchers have learned more about nutrition, it has become clear that the foods we eat play a much bigger role in our health than just preventing deficiencies. And in 2002, the Food and Nutrition Board completed a sweeping update of its guidelines. Now, instead of RDAs, we have Dietary Reference Intakes, or DRIs.
What are DRIs?
Unlike the RDAs, DRIs are made up of a range of figures. These include:
- Estimated Average Requirement (EAR): This figure represents an average daily intake -- in other words, one that should meet the requirement of half of all healthy people in a particular age group.
- Recommended Dietary Allowance (RDA): Based on the EAR, the RDA is the daily intake level that meets the requirements of 97% to 98% of all healthy people in an age group.
- Adequate Intake (AI): The AI is a level that should meet, or even exceed, the dietary needs of virtually everyone. It?s based on an estimate of the amount of the nutrient that is actually consumed by healthy people.
- Tolerable Upper Intake Level (UL): This is the highest amount of a nutrient that is likely to be safe for almost everyone in the general population. ULs are only set when there is strong scientific evidence that getting too much of a particular nutrient can be harmful.
Protein, Carbs, Fiber and More
In addition to updating its guidelines for vitamins and minerals, the NAS also made new recommendations for the amounts of carbohydrates and protein we should take in -- as well as how much exercise we need. And, for the first time, it set guidelines for fiber consumption.
Here?s a comparison of the old and new guidelines:
|New Guidelines||Old Guidelines|
|Carbohydrates||45 percent to 65 percent of total calories||50 percent or more of total calories|
|Fat||20 percent to 35 percent of total calories||30 percent or fewer of total calories|
|Protein||10 percent to 35 percent of total calories||10 percent to 35 percent of total calories|
|Exercise||60 minutes a day||30 minutes, most days|
|Fiber||25-38 grams a day||No guideline|
An hour of exercise a day?
An hour of daily physical activity sounds like a lot, especially for those of us who struggle to fit in even 30 minutes a day. But scientific studies have shown that an hour a day is how much exercise you need to lose weight and reduce your risk of chronic diseases.
Now here?s the good news: The hour doesn?t have to be done all at one time, and it doesn?t all have to be spent in the gym or on the jogging trail. All you need is a total of 60 minutes of moderately strenuous activity a day. That could mean, say, 30 minutes of brisk walking, along with a few shorter intervals of gardening, housework, etc., throughout the day.
If even that is too much on some days, remember that any amount of activity is better than none!
Fiber is the part of certain carbohydrate foods -- whole grains, fruits and vegetables -- that our bodies are unable to digest.
That doesn?t mean we don?t need it. Not only does fiber keep us regular, it can help stave off hunger pangs by keeping food in the stomach longer. And it benefits our hearts by interfering with the absorption of fat and cholesterol.
That?s why it?s important to read labels, and always choose those foods with the highest fiber content.
Strive for variety
The best part of the new dietary guidelines may be that they allow much more flexibility in tailoring a healthy eating plan to your own likes and needs.
Along those lines, there?s one important recommendation that hasn?t changed: Make sure to eat a variety of foods to make sure you get all the nutrients you need to reduce your risk of conditions like obesity, diabetes and heart disease -- and to keep you feeling and looking your best.
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