Monday, August 3, 2015

New Thinking About Calories

A paper just published in the American Journal of Clinical Nutrition has caused nutrition experts to rethink the adage – a calorie is a calorie.  In terms of weight gain in humans, “foods have complex mechanisms that help or hinder weight long term”  according to the paper’s authors.  Researchers from Tufts and Harvard Universities examined 24 years of data on 121,000 men and women.  Subjects were nurses and doctors from the Nurses’ Health Study and the Health Professionals Follow-Up Study.  Subjects, initially free of obesity or chronic illness, completed detailed food questionnaires.  Their weight gain was measured every four years, and results were adjusted for lifestyle changes such as physical activity, sleep, and total calorie intake.  The study found the following associations between protein foods and weight:
1) Meats, chicken with skin and regular cheese were associated with weight gain..
2) Milk, legumes, peanuts and eggs were not associated with weight gain or loss.
3) Yogurt, peanut butter, walnuts and other nuts, skinless chicken, low fat cheese and seafood were associated with relative weight loss.

Starches with minimal fiber, such as white bread, white potatoes, and white rice were associated with weight gain, and found to be similar to added sugar.  (Many breakfast cereals are almost entirely refined starch with added sugar.)

The take-home message from this paper, as I see it, is that protein foods vary greatly in their ability to keep you sleek and healthy.  Choose from groups 2 and 3 as often as possible, and always be mindful of the need for vegetables, fruits, fiber and healthy fats.

More on Fiber:  Another study from Harvard, published in BioMed Central Medicine, showed that middle aged and older subjects, followed for over 10 years, gained substantial benefits from whole grain foods.  Those who ate the most whole grain were 17% less likely to die in the study period compared to those who ate the least amount.  They were less likely to be obese, and less likely to suffer premature death from lung disease, diabetes and cancer.  People sensitive to gluten in wheat can still get plenty of whole grain and fiber from oats, quinoa, buckwheat, brown rice and corn.

,More on Vitamin D:  A recent study from Tufts University showed that a vitamin D supplement will be better absorbed when taken in a meal containing fat.  Fat stimulates the release of bile into the small intestine, which will make it easier for the body to absorb fat-soluble vitamin D.

Sadja Greenwood, MD, MPH

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