High fat diet good or bad?

A study by Gower and Goss was just published in the journal Nutrition examining the role of dietary fat in insulin resistance:

RCT: A lower-carbohydrate, higher-fat diet reduces abdominal and intermuscular fat and increases insulin sensitivity in adults at risk of type 2 diabetes.

From the abstract:

(AA is African American, EA is European American; PCOS is Polycystic Ovary Disease)

participants who consumed the lower-carbohydrate vs. the lower-fat diet lost more intra-abdominal adipose tissue (IAAT) (11 ± 3% vs. 1 ± 3%; P < 0.05). After weight loss, participants who consumed the lower-carbohydrate diet had 4.4% less total fat mass. Original to this report, across the entire 16-wk study, AAs lost more fat mass with a lower-carbohydrate diet (6.2 vs. 2.9 kg; P < 0.01), whereas EAs showed no difference between diets. As previously reported, among women with PCOS, the lower-carbohydrate arm showed decreased fasting insulin (−2.8 μIU/mL; P < 0.001) and fasting glucose (−4.7 mg/dL; P < 0.01) and increased insulin sensitivity (1.06 arbitrary units; P < 0.05) and “dynamic” β-cell response (96.1 · 109; P < 0.001). In the lower-carbohydrate arm, women lost both IAAT (−4.8 cm2; P < 0.01) and intermuscular fat (−1.2 cm2; P < 0.01). In the lower-fat arm, women lost lean mass (−0.6 kg; P < 0.05). Original to this report, after the lower-carbohydrate arm, the change in IAAT was positively associated with the change in tumor necrosis factor α (P < 0.05).”

Does this mean that a high fat (e.g. Atkin’s) diet is preferable for weight loss and prevention of diabetes? At least for certain populations, such as AA and PCOS, this may be so.

Fat mass change

Lower carbohydrate intake resulted in lower intra-abdominal fat (the more dangerous visceral pattern of adiposity) in the eucaloric diet (A) and with hypocaloric (B) diets. These results suggest that a low carbohydrate diet might be more effective than low fat for short term weight loss. These results are intriguing in light of the wealth of molecular and animal model studies suggesting metabolic harm from a high fat diet. As we have pointed out in this blog, people are not mice, which may account for some of these differences. Previous epidemiological work implicated processed sugar and starch as important drivers of weight gain, but they also suggest that sources of fat, such as processed meats, also promote weight gain. As has been pointed out before, the kind of fat seems to play a role in outcomes such as cardiovascular disease. Given these uncertainties, it is too early to give a blanket recommendation for high fat diets. A long term study of low fat versus low carbs on weight gain and metabolism will be important to sort this out.

Meanwhile read this from the BMJ are some diets mass murder?

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