Nutrition large and small

When people want to lose weight, they limit calories. Calories come from macronutrients: protein, carbohydrates, and fat. They are “macro” because we eat them in amounts ranging from tens to hundreds of grams per day.

Micronutrients, on the other hand, are eaten in tiny quantities of micrograms to a few grams per day, and do not provide calories. This includes vitamins, minerals, and other phytochemicals, such as beta-carotene.

Decreased macronutrients means decreased micronutrients

Researchers collected nutrition information from 291 women enrolled in a weight-loss study. The women were randomly selected to follow one of four diets:

• Atkins: 20 or fewer grams of carbohydrate per day initially, followed by a weight-loss phase of 50 or fewer grams of carbohydrates per day
• Zone: A diet with 40% of calories from carbohydrate, 30% from fat, and 30% from protein
• Lifestyle, Exercise, Attitudes, Relationships, Nutrition (LEARN): Behavior modification to help people eat less, exercise more, and meet Food Guide Pyramid goals of 30% or fewer calories from fat and 55-60% of calories from carbohydrates
• Ornish: Very-low-fat diet with 10% or fewer calories from fat

The women following three of the four diets were at risk for inadequate intake of the following micronutrients:

• Atkins: thiamine, folic acid, vitamin C, iron, and magnesium
• LEARN: vitamin E, thiamine, and magnesium
• Ornish: vitamins E and B12, and zinc

Compared to their usual diet, women on the Zone diet decreased their risk for low intake of vitamins A, E, K, and C and were not at increased risk for inadequate intake of other micronutrients.

Diet right, lose weight, and gain health

This study suggests that rather than strictly limiting a single macronutrient, such as carbohydrate or fat, a more balanced macronutrient approach may help you get important micronutrients while shedding pounds. Simply eating less overall, as promoted in the LEARN plan, may cause you to miss important micronutrients too.

To fill in the gaps when you’re dieting, focus on:

• Thiamine: oat bran, fortified cereals, lean pork, orange juice
• Folic acid: brown and white fortified rice, lentils, peas, beans, fortified cereals, orange juice, green leafy vegetables, okra
• Vitamin C: citrus fruit and juice, peaches, peppers, papayas, apricots, pineapple, strawberries, broccoli, Brussels sprouts
• Iron: beans and lentils, green leafy vegetables, fortified cereals, clams, lean beef (Tip: Cook your food in a cast iron skillet or pan to boost iron content!)
• Magnesium: fish, buckwheat, oat bran, green leafy vegetables, beans, nuts, seeds
• Vitamin E: nuts and seeds, canned tomato products, green leafy vegetables, vegetables oils, fortified cereals
• Vitamin B12: clams, lean beef and turkey, fish, fortified cereals, lean dairy products
• Zinc: oysters, fortified cereals, beans, lean beef, fish

Though it is generally advised to get micronutrients from your diet, taking a multivitamin supplement may help avoid deficiencies.

(Am J Clin Nutr; E-Pub Ahead of Print August 4, 2010)