Levitsky

Counts listed on foods reflect what someone with normal digestion would expect to absorb, according to Dr. Levitsky.

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Instead, companies make adjustments for how much of that energy will actually be absorbed by the body, which is about 98% for fats and slightly lower for carbohydrates and proteins, according to David Levitsky , a nutritional-sciences professor at Cornell University in Ithaca, N.Y.

Fire, Water and Fat: Science Used to Measure That Double Bacon Burger's Heft Isn't Perfect, but Comes Pretty Close Shirley S. Wang 2011

An allergy differs from celiac disease, whose sufferers, Levitsky said, can incur far-reaching health effects from eating gluten, including the inability to absorb nutrients.

The Diet That Shook Up Tennis? Tom Perrotta 2011

Such variations are usually quite small, likely far less than the amount of extra calories someone would consume by eating more of a particular food than they intended, Dr. Levitsky said.

Fire, Water and Fat: Science Used to Measure That Double Bacon Burger's Heft Isn't Perfect, but Comes Pretty Close Shirley S. Wang 2011

"It's mostly mental energy you're talking about, not energy supplied to muscle tissues," said David Levitsky, a professor of nutrition and psychology at Cornell University, when asked about the effects of giving up gluten if one has an allergy.

The Diet That Shook Up Tennis? Tom Perrotta 2011

"We're slaves to our environment," says David Levitsky, professor of nutritional sciences and psychology at Cornell, as he explains the rising level of obesity.

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"We're slaves to our environment," says David Levitsky, professor of nutritional sciences and psychology at Cornell, as he explains the rising level of obesity.

Carole Carson: Fitness and Obesity Trends to Watch for in 2012: It's Not a Small World After All Carole Carson 2012

"We're slaves to our environment," says David Levitsky, professor of nutritional sciences and psychology at Cornell, as he explains the rising level of obesity.

Carole Carson: Fitness and Obesity Trends to Watch for in 2012: It's Not a Small World After All Carole Carson 2012

"We're slaves to our environment," says David Levitsky, professor of nutritional sciences and psychology at Cornell, as he explains the rising level of obesity.

Carole Carson: Fitness and Obesity Trends to Watch for in 2012: It's Not a Small World After All Carole Carson 2012

Levitsky said a gluten-free diet might have benefits for those with mild allergies, or even no allergy at all.

The Diet That Shook Up Tennis? Tom Perrotta 2011