Advocates of low-carbohydrate diet are voicing concern about a recent paper that suggested the diet could cause weight gain, contrary to previous research. One expert has even called for its retraction.
The study, published in Nutrition & Diabetes in February, also found that the low-carb diet did little to prevent the progression of type 2 diabetes. Researchers have since criticized the study for drawing these conclusions based on data from a handful of mice, using a poor proxy for the human version of the diet.
One expert took to social media to warn against the study’s message regarding the low-carb, high-fat diet (LCHF); for instance, obesity & nutrition researcher and author, Zoë Harcombe from Newport, Wales, tweeted:
9 mice – yes 9 mice! were fed sucrose & oil/fat & these dudes think they've unpacked LCHF! https://t.co/pw6cdQo6mi Try meat & veg on people!
— Dr Zoe Harcombe, PhD (@zoeharcombe) February 19, 2016
Harcombe told us:
The paper was incredible (as in — lacking in credibility). It took 17 mice, genetically bred to be fat and sick, and put 8 on standard chow and 9 on a LCHF diet. You only study mice when it would be unethical to study humans. There are many human LCHF studies already…so why study mice? (Maybe because you didn’t like the human conclusions?!)
In addition, the diet given to the mice was far from what people on a low-carb diet eat, Harcombe said.
But based on its conclusions, the study was reported sensationally in the media, Harcombe noted, with headlines such as the Daily Mail‘s “The Paleo diet is ‘dangerous and increases weight gain’, diabetes expert claims:”
The paper was one thing. The way it was reported (sensationally and completely irresponsibly by one of the researchers) was another and the way the media reported it (with no critique/review/analysis/effort) was another still.
The recommendation [against the low-carb, high-fat diet] follows from presumed risk based on experiments with 9 mice from a strain bred for susceptibility to metabolic abnormalities. The study ignored the dozens of studies, listed in their own references, comprising hundreds of human subjects, that contradicted the mice data.
In the letter, Feinman calls for the paper to be retracted, and subject to new peer review from experts with experience in the LCHF diet in humans. He explains in the letter:
There are numerous papers demonstrating the value of dietary carbohydrate restriction. Our review (, reference (5) in Lamont, et al.) includes 77 references and documents the evidence that nothing is better than LCHFD for obesity, diabetes and metabolic syndrome. We do not think that this is the final word and we are open to criticism. However, a study of 9 mice for eight weeks does not raise questions about this extensive body of knowledge.
Calling the results “ambiguous,” he adds in the letter:
1. The LCHFD had better improvement than control on [triacylglycerol] TAG and HDL (“good cholesterol”) and there were no significant differences in total cholesterol or LDL. The ratio of HDL/TAG is considered one of the best indicators of CVD risk: the LCHFD conferred decreased risk.
2. The result that a reduction in dietary carbohydrate worsened glycemic control, if reproducible, would be a landmark phenomenon demonstrating that conditions could be found where an NZO mouse showed metabolic behavior completely the opposite of what is seen in humans. That increasing dietary carbohydrate will decrease blood glucose in humans is absurd and has been contradicted by thousands of recorded measurements.
3. Similarly, the result (Figure 1) that the low-carbohydrate mice gained more weight even though they consumed fewer calories makes no sense at all. In fact, in the numerous diet studies in humans, the low-carb arm almost always loses more weight and critics claim that that is only because they took in fewer calories.
“A low-carbohydrate high-fat diet increases weight gain and does not improve glucose tolerance, insulin secretion or β-cell mass in NZO mice,” has not yet been cited, according to Thomson Reuters Web of Science.
Co-author of the study, Sof Andrikopoulos, who is based at the University of Melbourne in Australia and is the current president of the Australian Diabetes Society, declined to comment. He told the Daily Mail:
Low-carbohydrate, high-fat diets are becoming more popular, but there is no scientific evidence that these diets work.
The news story also includes this quote from Andrikopoulos:
In fact, if you put an inactive individual on this type of diet, the chances are that person will gain weight…This level of weight gain will increase blood pressure and increase your risk of anxiety and depression and may cause bone issues and arthritis.
For someone who is already overweight, this diet would only further increase blood sugar and insulin levels and could actually pre-dispose them to diabetes.
Feinman, however, called Andrikopoulos’ reported comments “completely out of line,” warning in his letter:
In the end, it is people struggling with obesity and diabetes who are the real victims of this breakdown in scientific practice. There is a serious ethical issue in that Andrikopoulos’s paper and his reported public statements are intended to deny a treatment to people with obesity, diabetes and metabolic syndrome, a treatment that, in fact, is established as effective and safe and is even included in the “individualization” recommended by health agencies. It is impossible to tell how much harm has been done but retraction of the paper will be a start to correction.
But Feinman told us he doesn’t think the journal will retract the paper:
The Journal will not retract the paper since [there] is no evidence of fraud or falsified data. I will not pursue it since it is [biased] and poor judgement that is involved. It’s real importance is an example of the poor standards in the literature.
A spokesperson from Nutrition and Diabetes added:
We can confirm that Nutrition & Diabetes received the letter from Dr Feinman. We take issues related to research published in the journal seriously and we have offered Dr Feinman the option to submit a formal “Letter to the Editor” for publication in the journal.
Harcombe, on the other hand, said she doesn’t think the paper should be retracted:
I’m not a fan of censorship — although that is what the conventional side tries to do with our “unconventional” articles all too often.
Hat tip: Ben Gallarda
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