Tuesday, February 07, 2006

Dietary Protein = Satiety

Imagine my intrigue this morning as I started reading Sally Squires weekly column, The Lean Plate Club, in the Washington Post and saw that it included the work of Dr. Margriet Westerterp-Plantenga, an associate professor of human biology at the University of Maastricht in the Netherlands.

Ms. Squires article, Finding Satisfaction In Protein, is an interesting read - I'll explain why in a moment. So you understand why I was enticed by Squires choice of subject today - Dr. Westerterp-Plantenga was among the poster presenters at the 2006 NMS Scientific Sessions last month and I had an opportunity to discuss her findings with her during the meeting.

Where Ms. Squires got it right - the research data supports a mountain of other evidence that shows protein offers three benefits:
  • greater satiety when eaten in a higher quantity than currently recommended
  • less efficiency with more thermogenesis in the metabolic processes for digestion
  • a boost to the metabolism to burn more calories each day

In the study, researchers report for the first time that consuming nearly a third of daily calories as lean protein, such as lean meat or poultry without the skin, revs a person's metabolism during sleep. And the benefits aren't just nocturnal: The researchers also found that higher protein intake boosted the burning of calories and fat during the day.

Plus, when the study's participants, who were all women of healthy weight, ate more protein, they said they felt fuller, more satisfied and less hungry than when they consumed a diet with the typical amount of protein, about 10 percent of calories.

The findings suggest that increasing lean protein daily "enables you to reach the same level of satiety that you are used to with about 80 percent of your normal energy intake," notes the study's lead author, Margriet Westerterp-Plantenga..."That means you can eat about 20 percent less and still have the same satiety. . . . It's a very easy way to ingest" fewer calories and without feeling hungry all the time.


What gives protein its caloric edge? The amino acids that comprise protein are more difficult for the body to metabolize than either fat or carbohydrates. So it takes more energy to burn protein than other nutrients. The body also doesn't store protein as efficiently as it does carbohydrates or fat. So it's more likely to be burned, a process called thermogenesis. That in turn requires more oxygen and increases the feeling of fullness and satisfaction after eating.

So then, where did Squires get it wrong?

Well, for one thing she's remains convinced that weight loss requires severe restriction of calories, with a recommendation of just 1500-calories each day. For most men and women, this level of calorie restriction is counter-productive and will not lead to long-term weight loss. I've written about why reducing calories too much doesn't work recently in Getting the Calorie Intake Right for Weight Loss.

For another, she mistakenly thinks that Westerterp-Plantenga's findings can automatically be interpreted and utilized for weight loss. If you read the abstract, this was a feeding study, in a carefully controlled environment, designed with "isocaloric" energy intake - those participating were fed enough calories to maintain their calorie intake to maintain weight. It was also a 4-day study.

Now don't get me wrong here - there is ample evidence to support a higher protein intake (as percentage of calories) as part of a diet to lose weight. Ms. Squires just fails to mention this study was not designed to investigate weight loss related to protein intake. Not only that, she takes it a step further and tries to convince her readers that "...the latest findings don't mean it's time to dust off those high-protein, low-carb diet books. The protein-heavy Atkins diet included high fat and in some phases eliminated most fruit and vegetables. The current study limited fat to about 30 percent of daily calories, and included 40 percent of calories as healthy carbohydrates, including fruit and vegetables."

This is simply ignorant of the piles of evidence we have that supports diets low in carbohydrate for weight loss. But, what can you expect from someone so committed to the idea that fat makes you fat?

She does try though. And she even offers up suggestions to lose weight in this column - eat just 1,500 calories a day and eat 94g of protein to do so with a salmon fillet, 3-cups of skim milk and a skinless chicken breast as part of your daily food intake. Here's what she doesn't bother to tell you - even if you make the best choices for your other foods, you're still not going to meet or exceed your Recommended Daily Allowance (RDA) for essential nutrients.

In fact, you'll fail to eat enough to satisfy your essential fatty acid requirement and your requirements for fat soluble vitamins D & E, along with potassium, fiber and iron. And that's IF you make the absolute best choices - if you don't you'll miss even more essential nutrients.

So what's a better approach? How about one that not only satisfies your hunger, but also is rich with nutrients?

While Ms. Squires is quick to dismiss low carbohydrate diets in the mistaken assumption that they eliminate fruits and vegetables, keep in mind the facts - all low carbohydrate diets REQUIRE a minimum intake of fruits and vegetables that exceeds current dietary recommendations for that food group! Odds are good that if you choose a low carbohydrate diet as your weight loss strategy, you'll actually increase the number of fruits and vegetables you eat each day rather than reduce that number!

This was the finding of a recent survey conducted by researchers at SUNY Downstate Medical Center with participants from the Active Low-Carbers Forum as the study group. Of those completing the survey - over 3,000 individuals actively following a carbohydrate restricted diet - only 4.77% increased fat intake, another 10.23% reported increasing protein and 11.99% reported eating vegetables was an important part of their low-carb approach.

In fact, when getting into specifics, 80.34% reported increasing vegetable intake with 46.22% reporting they increased intake to at least double their usual consumpsion compared with a pre-low-carb diet.

Did fat intake increase? Probably when we consider that the vast majority reported they were following Atkins.

Did this hinder weight loss?

You decide...
  • 62.38% reported losing more than 30-pounds
  • 14.33% reported they didn't need to lose more than 30-pounds
  • of those with 30-pounds or more to lose, that lost 30-pounds or more, 64.98% reported keeping the weight off for more than one-year
  • 60.13% had their cholesterol measured before starting a low-carb diet
  • 62.15% reported their total cholesterol decreased
  • 57.96% reported their LDL decreased
  • 48.57% reported their HDL increased
  • 68.12% reported their triglyerides decreased

The last telling statistic is that 48.95% consulted with their physician before starting - with 55.77% reporting that their physician was supportive and other 28.28% reporting that their physician didn't have an opinion when they started but was encouraged after seeing the results!

Need I say more?

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