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Old 10-05-2010, 07:22 PM   #10 (permalink)
davej323
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Join Date: Jun 2010
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Quote:
Originally Posted by SaraR74 View Post
This study is inherently flawed, in that it tested the insulin response with variation of saturated fat intake independent of a low-carbohydrate dietary approach, and in testing insulin response they chose to ignore or downplay the significance of results that did not support their hypothesis and they attempt to discredit the standard typically used for measuring insulin response (fasting glucose), which can be a very effective means of measurement when used to develop individual trends over time. Furthermore, it seems to me that this study is a classic example of confirmation bias. It is obvious that the researchers set out to prove that it is possible to control insulin response even while following a high-carbohydrate nutritional approach. While this may be possible, the study did nothing to prove that diets higher in saturated fat can lead to insulin resistance when followed in conjunction with a low-carbohydrate nutritional approach. Let me also quote directly from that article in a few places, after which I am sure all of us following the Atkins plan can safely disregard this study:

"Additional research is needed to explore differential effects of low- and high-fat diets on weight loss, appetite behavior, satiety, insulin sensitivity, and cardiovascular disease risk factors in both the short and long term. Very little is known regarding long-term safety of high-fat diets and their long-term effects on metabolism and cardiovascular disease risk."
All this says it that more research is needed. Since low carbohydrate nutritional plans have been studied for nearly 150 years now, and have been shown to be effective in weight loss and the control of T2 diabetes, I am not sure what further research these people need to see.

"Recently, two randomized controlled trials that compared the longer term effects (6 months to 1 yr) of traditional low-fat diets vs. ad libitum high-fat diets have received a great deal of attention (40, 41). Foster et al. (40) compared the efficacy of the low-carbohydrate (initially restricted to 20 g carbohydrate/d), high-fat Atkins diet with a conventional low-fat (25% of calories), low-calorie diet (12001500 kcal/d in females and 15001800 kcal/d in males) in otherwise-healthy obese subjects (mean BMI, 34 kg/m2). The high-fat diet produced a greater weight loss than the low-fat diet after 6 months (6.7 vs. 2.7 kg), but at 1 yr, the amount of weight loss was not significantly different between the two groups (4.3 vs. 2.5 kg)."
This simply means that, at one year, a low-fat diet shows to also be effective in terms of weight loss. 4.3kg versus 2.5kg does seem like a significant difference to me, but I realize that the term "significant" is subjective. Nobody following or supporting the Atkins plan would ever suggest that it is the only effective means to lose weight or control diabetes, so this will not serve as a revelation to any of us.

"In the second study, Samaha et al. (41) compared the effects of a low-carbohydrate (≤30 g/d), high-fat diet vs. a low-fat (≤30 g/d) National Heart Lung and Blood Institute diet (43) designed to create a caloric deficit of 500 kcal/d. Their subjects were severely obese (mean BMI, 43 kg/m2), and most were African-Americans, hypertensive, and characterized by either type 2 diabetes or the IRS. In this 6-month study, subjects on the high-fat diet lost more weight than those on the low-fat diet; however, the amount of weight loss was low (5.8 vs. 1.9 kg), and the dropout rate was again very high, particularly in the high-fat diet group (47 vs. 33% in the low-fat diet group), indicative of pervasive noncompliance. The authors also emphasized that the high-fat diet led to greater improvements in insulin sensitivity than the low-fat diet group, but these effects were minimal, and the authors again used a suboptimal index based on fasting glucose and insulin levels as a measure of insulin sensitivity."
Here is an example of disregarding evidence that does not support their hypothesis. The high-fat diet was more successful in improving insulin sensitivity, so they suggest that the high-fat displayed displayed "pervasive noncompliance," when in fact there were significant dropouts in both test groups. They also use subjective terms such as "low" and "minimal" again. They did not even bother to mention the actual values of these "minimal" effects. It is very obvious that they are trying once again to discredit any evidence that doesn't support their hypothesis.

"With respect to saturated fat, epidemiological studies show that high intake of total and saturated fat is associated with insulin resistance, and this relationship may be dependent on increased body adiposity (54). However, multiple cross-sectional studies have found that intake of both saturated and trans FAs is associated with hyperinsulinemia and with risk of type 2 diabetes, independent of general obesity (55, 56, 57). High intake of polyunsaturated FAs (PUFAs) does not appear to have the same adverse effects and may even result in an increase in insulin sensitivity (58). For example, Summers et al. (59) recently studied the effect of substituting dietary saturated fat with polyunsaturated fat on insulin sensitivity in healthy, obese, and type 2 diabetic subjects. Their findings demonstrated that an isocaloric diet enriched in polyunsaturated fat resulted in both an increase in insulin sensitivity assessed by glucose clamp and a lowering of LDL cholesterol when compared with a diet rich in saturated FAs. However, it was not possible in this study to conclude whether it was the increase in dietary PUFA or the decrease in saturated fat that produced the relative benefits in the PUFA diet subgroup. In addition, diets enriched in polyunsaturated fat have not consistently been shown to improve insulin sensitivity (60), and long-term intervention trials have not been conducted. Discrepancies in the short-term studies are often attributable to the failure to control for dietary FA and carbohydrate composition (e.g. amount of MUFA), total calories, physical activity, and population characteristics such age, gender, and adiposity."
Well, I don't think this is really news to anyone. An increase in saturated fat intake can have many adverse effects when you isolate that factor across the entire population. Even this study recognizes the fact that these results are not reliable when carbohydrate intake, as well as other disincluded factors, are not considered.

I could go on in pointing out the errors, bias, and inconsistency in this study, but I think I made the point. Atkins folks, you can safely disregard this study. Thank you for trying to help us, Sara. This study was no help whatsoever, but we appreciate your concern.
__________________
Dave
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Male, 6'0" tall, 37 y/o

Starting weight, 4/19/10 (started Atkins) = 287
6/16/10 (finished Atkins book & joined Fitday) = 261
10% by New Year challenge starting weight = 251
latest weight 10/25/10 = 241.5
10% by New Year challenge goal = 226
ultimate goal for lifetime maintenance by 4/19/11 (one year mark, 100 pounds loss) = 187
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