More on dairy and weight loss including the theory behind it

[Guest guest]

Weight loss was greatest in subjects that took their dairy in the form of

food (not supplements).

By Tallmadge

Is it possible that one of my favorite food groups -- milk and milk

products -- not only provides crucial nutrients but can also help people

maintain and lose weight? The answer, while not yet conclusive, looks

encouraging. New studies are finding that calcium, particularly when in milk

products, may help shed unwanted pounds and body fat.

This is doubly important news because many people slash milk products from

their diets to lose weight. The research is showing that move is not only a

mistake for your bones, blood pressure and overall health (which nutrition

experts have been saying for years), it may also make weight loss more

difficult.

Uncovering the calcium-weight loss connection was, like many scientific

discoveries, a case of serendipity. In the 1980s, scientists researching the

positive effects of calcium on blood pressure found that people on

higher-calcium diets not only lowered their blood pressure but also lost

weight. The connection wasn't taken seriously at the time. But when large

government- funded studies found links between calcium intake and body

weight, researchers decided it was worth looking into.

Since 2000, observational and clinical studies of men, women and children

have consistently shown that people eating diets containing calcium's

recommended dietary allowance of 1,000 to 1,300 milligrams per day have

lower body weights and lower body fat. In fact, it's been calculated that

with 300 more milligrams of calcium daily, adults will weigh about seven

pounds lighter than they would without the calcium.

All of the biological mechanisms aren't completely understood. But, after

many years of animal studies, the scientists, led by Zemel, director

of the Nutrition Institute at the University of Tennessee, have formulated

the primary reason for this weight loss. When there isn't enough calcium in

the diet, the body responds by releasing hormones to help conserve as much

calcium as possible for critical bodily functions (heartbeat, for one). One

of these hormones, calcitriol, tells arterial muscle to contract, which

increases blood pressure. But calcitriol also acts on fat cells.

" Calcitriol sends the fat cells a message to start making more fat and

sends another message to slow down the process of fat breakdown and

oxidation, " says Zemel, co-author of " The Calcium Key " (Wiley, 2004). Since

high calcium levels have been the norm through evolution, the body assumes

that food is scarce and conserves when calcium is low in the diet.

The result is that we become more efficient at storing calories as body

fat, so when we cut calories to lose weight, a low-calcium diet makes it

harder to break down body fat. Higher-calcium intakes (in which the body

senses, rightly or wrongly, that there is plenty of food around) cause lower

calcitriol levels and increased fat breakdown. So weight loss is harder for

people who don't consume enough calcium, which is the case for average

Americans, most of whom consume only half the daily calcium requirement.

In the first human clinical study of the calcium-weight loss connection,

Zemel and his colleagues found that the amount of calcium and its food

source made a huge difference in weight loss results.

In the study published in Obesity Research in April, three groups of people

ate low-calorie diets containing 35 percent fat, 49 percent carbohydrates

and 16 percent protein. The first group, which ate 400 to 500 milligrams a

day of calcium (an amount of calcium typical for many Americans and less

than the minimum requirement) lost an average of 15 pounds in six months.

While eating the same diet with an additional 800 milligrams of calcium

from a supplement, the second group lost 19 pounds. But while eating a diet

high in milk products containing about 1,200 milligrams of dietary calcium

per day (not from a supplement), the third group lost 24 pounds. Fat loss

followed a similar pattern. The people on the high-dairy diet lost a higher

percentage of body fat, maintained more lean muscle and (a finding that

surprised the researchers) lost more belly fat, known as a risk factor for

diabetes and heart disease. In fact, the high-dairy group significantly

improved its insulin sensitivity, but it isn't known whether that was a

dairy effect or the result of the weight loss, which alone improves insulin

sensitivity.

Why milk products produced more loss in weight and body fat than calcium

supplements isn't completely understood. But there are some theories. For

example, milk products have many biologically active compounds, similar to

the phytochemicals in plants, which work synergistically to produce a more

powerful effect than a single compound, like calcium alone. And milk

products also contain unusually high levels of an amino acid (the building

block of protein) called leucine.

" Leucine plays a unique role in stimulating protein synthesis and is very

important for maintaining lean muscle mass, especially during weight loss, "

says Layman, protein researcher and professor of nutrition at the

University of Illinois, Urbana-Champaign. " If you eat a higher-protein diet,

with high levels of leucine coming from dairy products, during weight loss

you'll lose 80 percent body fat as opposed to the usual 60 percent body

fat. "

Until more human clinical research can verify these findings, remember that

calcium or milk products alone won't cause you to lose weight. Calories

still count. But while this research is being verified, it can only help to

consume three milk servings a day. Studies show people who consume more

milk products have diets higher in many beneficial nutrients such as

calcium, protein, Vitamins A and D, riboflavin, phosphorous, potassium and

magnesium.

Calcium researchers recommend three to four servings of high-calcium milk

products, containing about 300 milligrams of calcium per serving, per day.

About 1 cup milk, 1 cup yogurt or 1 1/2 ounces hard cheese are the best

examples. Here are some sources from " The Calcium Key " (Wiley, 2004):

FOOD AMOUNT CALORIES CALCIUM (GRAMS)

Buttermilk 8 ounces 91 264

Nonfat milk 8 ounces 86 301

Dry skim milk 3.5 tbls. 80 330

Brie cheese 1.5 oz 142 78

Cheddar cheese 1.5 oz 171 307

2% cottage cheese 1 cup 203 155

Hard parmesan 1 ounce 111 336

Plain nonfat yogurt 1 cup 127 451

Low-fat fruit yogurt 1 cup 225 313

Other tips:

€ Check the Nutrition Facts Panel on your food label. A good source of

calcium contains at least 30 percent of your daily requirement. Also, check

the calories and saturated fat: How many calories or saturated fat grams

does it take to get more calcium from the food? For people watching their

health or weight, the more nutrient-dense and the lower in calories and

saturated fat, the better.

€ If you're lactose-intolerant, remember yogurt is usually tolerated and

cheese contains no lactose. You can also try lactose-reduced products or

drink smaller amounts of regular milk products through the day.

€ A note to vegans: Protein researcher Layman says the equivalent of

one cup of dairy milk would be 1 1/2 cups of calcium-fortified soy milk, in

terms of the amount of leucine, an amino acid. No studies have been

published on soy products and weight loss.

-- Tallmadge

© 2004

Tallmadge is a Washington nutritionist and author of " Diet

Simple " (Lifeline Press, 2004). Send e-mails to her at food@....