A Tale of Two Cheese Sandwiches

Posted on January 17, 2012

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Another study, this time about whole food (WF) vs. processed food (PF)…

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2897733/

If two meals contain the same nutritional components, our bodies shouldn’t care whether the nutrients are sourced from whole foods or processed foods, right?  After all, nutrients are nutrients. At least that’s what the food industry has led us to believe during the last 30 years.

In a 2010 study, researchers from Pomona College in California wanted to see how subjects’ metabolisms reacted to a whole food meal (WF) vs. a processed food meal (PF).  So they employed the ubiquitous cheese sandwich and a group of 17 people.

Actually, it was two cheese sandwiches…

The WF cheese sandwich was made from Sara Lee Hearty & Delicious 100% Multigrain bread and Sargento Natural Medium Cheddar cheese. The PF sandwich featured Weber’s Enriched bread and Kraft Single American cheese. All subjects were served both sandwiches twice. (Note: the WF sandwich was not entirely “whole” because both the bread and cheese contained additives. However, it was minimally processed by U.S. standards.)

Then the researchers measured a lot of stuff before and after each meal. Here’s what they found:

1. The WF meal was perceived as more palatable.
2. Satiety levels were the same for both meals.
3. The WF meal prompted a greater energy expenditure than the PF meal.

…the metabolic processes associated with DIT consumed approximately twice as much energy for the WF meal compared to the PF meal.

What does that last part mean? First a quick lesson on metabolism.

Metabolism is made up of three components:
BMR (basal metabolic rate) – the energy expended at rest.
AMR (active metabolic rate) – the energy expended during exercise and daily living activities.
DIT (diet-induced thermogenesis) – the energy expended from food.

For this study, researchers were most interested in DIT response. What they found is the WF sandwich prompted a more active metabolic process than the PF one. In fact, it was twice as active! Apparently, the PF sandwich didn’t prompt as much metabolic activity because it was easier to digest.

Why was it easier to digest? In the quest to make foods easier and cheaper to produce, manufacturers often strip ingredients of certain nutritional elements. In the case of white bread, the wheat and bran are removed during the milling process. The process makes it easier for the manufacturer to make a lot of bread but it eliminates fiber, protein and other nutrients. So the body doesn’t have to metabolize those nutrients.  Sometimes the nutrients are added back in but it’s done at a refined level, not a whole food level. Hence, processed food arrives on our plates sort of pre-digested. (Ewwww!) Everything is already broken down. Our bodies don’t have to expend as much energy to do the work of metabolizing it.

If it’s easier to digest, then wouldn’t it be better for us? Nope. (Not unless you’re an astronaut in space.) Our bodies need to be active to stay healthy and maintain an ideal weight. Our metabolisms need to be revved. If studies show that 80% of ideal weight is due to food choices, wouldn’t we want foods that increase our metabolic levels? Whole foods operate at a higher metabolic level. Most processed foods do not.

In fact, processed foods could be detrimental.

According to the study, the PF meal prompted a DIT drop below the BMR curve six hours after the meal. What this means is that the PF meal made the subjects’ metabolisms even less active than their normal resting level. That’s lazier than lazy! And that’s just one little cheese sandwich.

See for yourself:

Average increase in metabolic rate (±SE) above basal metabolic rate for 6 h after whole (□) and processed (▴) meal trials for 17 healthy individuals.

The study seems to suggest that a diet rich in processed foods means a body poor in metabolic processes. That kind of diet can put our bodies into a lazier-than-a-hibernating-bear state. So we have to eat far fewer calories than we think to maintain an ideal weight.  And/or we have to exercise like mad to rev our systems. This explains why many people have trouble losing weight despite eating a normal number of calories. Processed foods may wire our bodies to expend less energy.

Somehow, I am not all that grateful to the food industry for creating the equivalent of pre-digested Franken-foods that send my metabolism into hibernation mode. That is one convenience I could do without.

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