Fat And Your Diet: Energy or Enemy?
"Eating at McDonald's is roughly equivalent to smoking four cigarettes ... as far as decreasing blood flow ..."
-Robert A. Vogel, M.D., University of Maryland, presenting data on the Mediterranean diet
| By Donna Marlor
R.D., M.A. |
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Every spring I make it a point to attend a major nutrition conference, just to keep up on the latest research. This year's choice was an international conference hosted by the American Heart Association titled "Lipids and Fatty Acids in Cardiovascular Disease."
"Fat," I told my girlfriend. "The conference was about different kinds of fat." It was a few
days postconference and I was back out on the usual "Saturday" running loop. Husbands and dogs were in the lead, we were behind, carrying out important dialogue about "stuff" in our lives.
"Fat," my friend seemed to be searching for some rational reason that I would fly 1,000 miles to hear about fat. "Really."
As we paused to hop over a fallen tree, I tried to give her a few conference highlights.
"It is kind of complicated to explain." I told her. But I gave it a try. "The basic message seemed to be that saturated fat really is the bad guy, but total calories count, too." We were getting hotter, and further behind the guys. Time to speed up. "I'll write about it in Silent Sports."
She nodded, too out of breath to talk. After all, I thought, learning about fat is a lot like eating it – the
information takes a little longer to digest. So what's new about fat metabolism? Keep reading.
Can Saturated Fats Make You Slow?
Most everyone by now knows that saturated fat can raise harmful LDL cholesterol. This "bad" cholesterol creates arteries that resemble no-wax ski bottoms, when a skating ski finish is the goal. Smooth artery walls mean less resistance, and blood can literally "glide" around in the body.
Just like a fast pair of skis, arteries also need to have some "camber," or elasticity. That way, when muscles
scream for oxygen delivery, arteries can dilate and allow for maximum blood flow. Few athletes smoke because they know nicotine constricts arteries, and also causes damage to the walls of the artery. Probably less well-known is that so does a load of saturated fat. Dr. Robert Vogel, of the University of Maryland tested this theory out on himself.
"I ate a fast food meal of 900 calories and 50 grams of fat," he told the audience at the Lipid Conference,
"and then I measured blood flow before and after the meal ... look what it did to my brachial artery (in his upper arm)." He had an ultrasound of his artery, sort of an X-ray-type of picture for us to look at. Clearly, the artery had "shrunk" after eating his high-saturated-fat meal.
"This was what two egg and sausage McMuffins will do."
I was impressed. It looked like the kind of breakfast you would want to serve your worst competitor before
a race. Then Vogel presented some other test meal data, using "healthy" fat sources. In this experiment, a 50-gram fat meal using either canola oil, olive oil or salmon had been compared for their effect on blood flow. I strained my eyes to see the slide. Was I seeing correctly? Not too surprising, salmon had come out on top, causing a mere 2% decrease in flow. But canola oil was in second place, and olive oil in last.
"Before you draw conclusions," Vogel cautioned, "take a look at this." Results were better for olive oil when it was combined with balsamic vinegar and vegetables. "We think this is why the Mediterranean diet is effective (for heart disease); it's not just the type of oil, it's the whole eating pattern."
Carbohydrate Use Can Be Affected by Fat
"What about athletes?" I knew someone in the audience would raise that question. True, it was looking like saturated fat was particularly bad for inactive people, but how did it affect those "different" folks?
"We're not sure," said Greg Cooney of the Garvan Institute of Medical Research in Sydney, Australia. "We
know that they can turn over fat stores more quickly."
Some discussion followed. No one seemed to be too concerned about what's known as the n-3 fatty acids (canola oil), or EPA and DHA (fish). These fat sources appeared to be readily oxidized by cells.
"All we can say for sure right now," said the Australian, "is that saturated-fat accumulation almost has a toxic effect on the cell."
I'll spare you the biochemistry, but ultimately his definition of "toxic" meant impaired ability to metabolize carbohydrates. Not good, if your passion in life is endurance sports.
How Much Fat Should Athletes Eat? The next speaker was Peter Zock, of Wageningen University, the Netherlands. Looking pretty fit himself, he
talked about the need to differentiate athletes from the sedentary population.
"We are considering raising the fat recommendations for athletes (without cardiovascular risk factors) to 40% of total calories from fat." There was some rustling in the audience. After all, this was the American Heart Association he was talking to. "But we still would limit saturated fats to 10% of total calories," he was
quick to add. "And for the sedentary population, we were thinking more about a range, from maybe 15%-30% of total calories."
Poor Peter didn't get much support from his American audience. After all, they reasoned, if you tell the American public they can eat up to 40% of their calories from fat, you can be sure that each and every person would consider himself "active" and load up – and they weren't talking about loading up on fish. In
the end, "cultural sensitivity" was deemed an essential factor in making recommendations for a healthy diet – and the United States stuck with a 30% limit.
Putting Advice On The Table
This isn't a recipe column, but when you get right down to it, at some point you're going to have to translate scientific evidence into a form that you can eat. That's basically my job description. To help you get started on a Mediterranean pattern of eating, I'll give you a few pointers. First, remember that "Mediterranean" includes more than just Italy. Don't forget about those delicious Greek recipes, too.
For a quick lunch, dump the traditional BLT, and whip this sandwich up instead: 1/8th of an avocado, thinly sliced; a few slices of red onion; and a little romaine lettuce. Put between your favorite whole-grain bread, lightly toasted.
Need a midmorning snack idea? Try any nut butter, such as pistachio butter, hummus or peanut butter with toasted whole-grain pita bread. Combine it with a serving of fresh fruit to get the anti-oxidant-quelling effect that keeps blood moving.
Dinner is the biggest problem meal for many people. This is where fish is a real lifesaver. If you don't know how to cook it, try buying a prepackaged frozen fillet, complete with marinade. Made by Northern Chef, all you have to do is follow the directions on the package for a quick and easy meal. If you're not a fish eater, opt for poultry and legumes as protein sources. Lean meat isn't forbidden on a Mediterrranean diet, but limit
it to about four to five ounces per week. Summer is a great time to grill, and skewering up some marinated vegetables is an easy way to "go Mediterranean."
Changing to a new pattern of eating requires some effort on your part. The good news is you should feel the difference from a better diet within six weeks. Why not give it a try?
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