2013 Nutrition and Metabolism Symposium

Is a Calorie a Calorie?

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The topic of the Nutrition and Metabolism Symposium (co-sponsored by the Nutrition and Metabolism Society the American Society of Bariatric Physicians) in 2013 was "Are All Calories Created Equal?" The basic understanding is, as the saying goes,"calories in, calories out" -- in other words, if we consume the same calories as we expend, our weight will be stable. I like to say that "calories in, calories out" is a description, but people try to use it as an explanation, which is sometimes where trouble starts.

The question of the day is whether the metabolic effects of calories from different sources may be different, often depending on context.

The Thermic Effect of Food, Donald Layman - The thermic effect of food is basically the calories it take to digest and utilize the food we eat. Overall, it takes about 8% of the calories from the food to digest and use it, but with protein it actually takes 20%. This is because there is a constant turnover of protein in our bodies, because we use protein for so many things.

Enough Protein for Breakfast! I've spoken about Dr. Layman's research about protein before, and it has progressed since then. His bottom line recommendation is to eat 30 grams of protein three times per day. This is especially important at breakfast. (If the source of your protein is from plants, you'll need 40 grams.) He says this is because an amino acid called leucine stimulates muscle synthesis in our bodies, but there has to be a bunch of it all at once for it to work optimally.

We tend to eat less protein at breakfast and much more at dinner, so equalizing the protein across the meals is a good goal. Layman's other dietary recommendation for his patients is to eat the same volume of starch as protein, and fill the rest of the plate with vegetables and fruit. Another talk by Heather Leidy emphasized the importance of protein in appetite control.

Caveat: I have to add that the "30 grams" provoked some discussion about whether this is a necessary recommendation for everyone. Some people who are adapted to a low-carb diet gain weight or stop losing if they eat too much protein, because some of it gets converted to glucose. Whereas it's clear that eating more than 30 grams in a meal doesn't carry additional advantage for muscle synthesis, the protein synthesis "ramps up" between 20 and 30 grams, so 20 or 25 grams may work for some people. Also, some protein sources, such as whey, have more leucine, so you can eat somewhat less to get this effect.

Dr. Patty Siri-Tarino works with Dr. Ronald Krauss. This group did the seminal work on particle size in LDL cholesterol and related issues. She was also the lead author one of the major meta-analyses showing that saturated fat consumption is not related to heart disease or stroke. In particular, eating carbohydrate instead of saturated fat is a bad idea.

Dr. Teresa Nicklas, an epidemiologist, demonstrated how the same data from observational studies can be analyzed in different ways and have very different outcomes.

She gave an example of a study that "showed" that eating eggs was associated with health risk factors. But if you look at patterns of egg eating (in other words, what else people eat when they eat eggs) you find that the negative outcome is explained by the people who essentially eat a lot of junk with their eggs -- this group had such bad outcomes that it made all the people who make healthier choices look bad. So the eggs themselves turned out to be fine. Which isn't surprising considering that more controlled studies generally show positive effects for egg-eaters.

Dr. Suzanne Devkota talked about her research about how different fats affect our gut flora. Bottom line on the emerging research so far: omega-3 fats good, omega-6 fats not so good, lard neutral. Some of her most recent work done with a "highly processed milk fat" (she emphasized that this isn't the same thing as just drinking milk or eating dairy products) found in ice creams, chocolate, and other processed foods. This one really threw the gut flora out of whack.

Gary Taubes gave us some history of how the hormonal hypothesis for obesity got lost during and after the second World War, because much of the research was German and got swept away both in anti-German sentiment and a change from the German being the main scientific language to English. (My mother was a chemistry major in college during the war and had to learn German as part of her studies. Not too many years later this was no longer the case.) Gary Taubes ended his talk by saying that we are still very far from understanding many things about diet and health, but "we have enough observational studies" for now, and should work on testing the many hypotheses generated from them instead of doing more of the ever-popular observational studies.

Jeff Volek talked about ketones, how the body uses them, and the advantages of a ketogenic diet. He showed research showing that ketogenic diets tend to be anti-inflammatory, improve insulin sensitivity, possibly alter some gene expression, and improve body composition with weight loss compared to other weight-loss diets. He says that to know whether you have optimal ketone levels, it's best to check blood rather than urine. There are test trips and meters made specifically for this. (The most popular is a Precision meter which tests both blood glucose and ketones. Strips are expensive! If you want to try this, order from Canada or try Ebay.)

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