Sci Am article

[Aaron_F]

Okay where to start
This Article in sciam was posted elsewhere by GiO and I thought I would make a few comments on certain bits, from a different perspective to the author, the renown epidemiologist Walter Willett.
The first main piece that comes up is this comment of

Quote[/b] ]"Since 1992 more and more research has shown that the USDA pyramid is grossly flawed."

It is not completely flawed, but most peoples perceptions of it (and enforced by the media) is wrong. Most low fat morons work around a total of 0 fat 90% carbs and minimum protein. This isn't what the pyramid is meant to represent, but is the common view.

Quote[/b] ]"Because saturated fat represents about 40 percent of all fat consumed in the U.S., the rationale of the USDA was that advocating a low-fat diet would naturally reduce the intake of saturated fat"

This practice as been commonly used around the world, (UK, a large percentage of European countries and Australasia), why? Because people are in general ignorant to what is in foods. Reduce your fat, so they eat margarine cos it has less fat (yes this is true!!&#33. People don't know what saturated fat is, but they know where the predominant food sources of fat in general are, so that was the theory. But, because of this, and stupid media garbage, has lead people to think all fat is evil and must not be eaten.... and also not helped by advertising of the food industry trying to hype up their new product ranges.

Quote[/b] ]"the early 1990s controlled feeding studies had shown that when a person replaces calories from saturated fat with an equal amount of calories from carbohydrates the levels of LDL and total cholesterol fall, but the level of HDL also falls."

This is commonly used by Willet to show some effects of higher carb diets, but this is one failing of being an American researcher (by that, Americans only generally read American texts....) and being an epidemiologist. Replacing saturated fat with carbs, can decreased HDL/LDL and increase tags. BUT, this is predominantly when they are being replaced with refined and/or high GI carbs. When replaced with fruits/veggies and low gi carbs, the effect is in general nil...

Quote[/b] ]"The best alternative is to conduct large epidemiological studies in which the diets of many people are periodically assessed and the participants are monitored for the development of heart disease and other conditions. One of the best-known examples of this research is the Nurses' Health Study, which was begun in 1976 to evaluate the effects of oral contraceptives but was soon extended to nutrition as well"

Way to hype his own research. While he mentions biases in other styles of research, he seems to coincidentally sidestep the common problems with cohorts, such as selection biases (all the people are nurses or doctors, not typical everyday people), and also the major bias cohorts, the loss of subjects overtime. His paper also measured food intake on several occasions over 20 years with a food frequency questionnaire, which while he will say his version is great, in reality all FFQs are unreliable.

Quote[/b] ]"But large epidemiological studies have shown little evidence that total fat consumption or intakes of specific types of fat during midlife affect the risks of breast or colon cancer"

Mainly because epi studies have too many flaws, and other potential affects that once adjusted for everything else, there is little real evidence to show for anything. For the likes of his research (nurses health and physicians) show no effect of fibre on colon cancer, but the European EPIC work shows a reduced risk with more fibre (possibly due to the fact that basically all the American data was on people eating <25g fibre/day)
To have an effect of fat on cancer, it has been theorised that you should be eating <20% fat/day, which is utterly unlikely for the most part.

Quote[/b] ]"Also, the process of storing dietary fat in the body may be more efficient than the conversion of carbohydrates to body fat"

This has been the utter, largest, most misconstrued concept of the low fat age. Sure, the conversion of carbs to fat is in general nil (there are exceptions). But this isn't how carbs make you fat, they make you fat by making you store the fat you eat, into adipose (but only when in caloric excess)

Quote[/b] ]"But recent controlled feeding studies have shown that these considerations are not practically important."

No s$^#
his entire section entitled "Carbo-Loading" shows the problem with telling people to eat carbs, expecting them to eat one thing and having them eat another (if you tell people to eat more fish, they generally start eating more deep fried battered fish, aarg)

Quote[/b] ]"In our epidemiological studies, we have found that a high intake of starch from refined grains and potatoes is associated with a high risk of type 2 diabetes and coronary heart disease.... Conversely, a greater intake of fibre is related to a lower risk of these illnesses"

I cant remember the article completely, but the potatoes are lumped in with the refined grains (white breads etc), which means its still generalising to say its both potatoes and grains, when the larger effect could be the grains. Also, he doesn't go into depth to say where the source of potatoes was (ie was it from McDonalds? Hashbrowns or the like?)

Quote[/b] ]"Overweight, inactive people can become resistant to insulin's effects and therefore require more of the hormone to regulate their blood sugar"

Emphasis should be placed on the word INACTIVE, because you can still be overweight and insulin sensitive. Strange that inactive people dont need as much carbs innit.

Quote[/b] ]"But the highest rates of fractures are found in countries with high dairy consumption, and large prospective studies have not shown a lower risk of fractures among those who eat plenty of dairy products."

This has to be the dumbest statement he could make. Sure certain countries have high dairy consumption, and they may have high fracture rates, but are they the same people.?
IT should also be noted that no prospective studies have shown high dairy = low fracture. Why?
Because how long have people known about osteoporosis, and how many years does it take to measure dairy intake from BIRTH to say 60-80 years.... seeing as the longest running epi research has only been running 30 or so years, and started on old men, how the hell is the research meant to be done now. Duh!!! Look at any Research on children, and Bone mineral density (measured by DEXA) is directly related to dairy/calcium intake and also those who eat the lowest dairy are of increased risk for fracture. I know a large number of people who would have a large bone (sic) to pick with his statements.

Quote[/b] ]"The USDA may not be the best government agency to develop objective nutritional guidelines, because it may be too closely linked to the agricultural industry. The food pyramid should be rebuilt in a setting that is well insulated from political and economic interests. "

This much is true, but its interesting that the rest of the world, who's dietary recommendations are not created by the dept of agriculture, have similar recommendations. A large amount of the work in the US (in terms of dietary intakes of protein, carbs fats and vits/mins) is carried out by the national academy of sciences, NOT the USDA. While the USDA may make the pyramid, they don't make the main nutritional recommendations.
What is really needed is to increase the knowledge of people in terms of what they put in their bodies. Regulations to limit the garbage put out by corporations as 'health conscious foods' and also something to try and get people to get off their lazy butts. The pyramid (and its peers all over the world) were all created to try and get some easy information to the public, but unfortunately the public is in general too ignorant to known any different.
I definitely do not recommend a LOW fat high carb diet, because that isn't suitable for most peoples purposes (unless you are an endurance person maybe). I recommend sane intake of whole foods, fruits veges, an intake of fish, meat poultry and the likes and a sane intake of fat (preferably unsaturated). And I didn't write it to say carbs are great yada yada yada. Its just that currently in the media, and especially on BB oriented boards they get a hard time, basically being akin to the devil, which of course they ain't. They can be bad, but so can being obese. Time and time again on the web you have people saying, I blew up 10lbs from eating a bite of <enter carb source here> which is impossible.
Bottom line, eat your veggies, eat some fruit, eat some protein and get some fat. Eat too much ... you get fat, eat too little you get thin.

 

[Aaron_F]

What, none of you guys have comments to make?

 

[vicious]

I agree with most of what you said, except the Food Pyramid, which is sort of drilled into our heads from an early age.

It was only a few years ago it was agreed that you had to eat a pretty hefty amount of carbs to gain muscle. Then people started trying to gain muscle with eating low-carb diets, then doing these CKD/TKD diets to get the "best" of both worlds. Eh?

But I'm a big fan of the Zone diet, which stresses balance. He's off with athletic-specific training (again, common knowledge to any experienced Zone user) In terms of general well-being, my God it's so much better than the low-fat, high-carb systems I've been on.

cheers,
Jules