If I buy olives, sundried tomatoes and anchovies from an Italian gourmet shop and put them in a blender, do I then have tapenade from that Italian gourmet shop?
That, in a nutshell, is the question about the science behind personalized weight loss programs.
When a company claims that it uses scientific evidence to build personalized prevention plans, it often means its experts picked risk factors and weight loss strategies from the scientific literature. It does not mean that the "blending," the design of these personalized plans, is supported by scientific evidence. Not at all.
According to The Wall Street Journal, health insurance company Aetna has signed up six firms to offer personalized weight loss to their employees through the genetic wellness program of Newtopia. Aetna had first tried the program on its own employees in a scientific study, which was published last month in the Journal of Occupational and Environmental Medicine. Aetna claims that "more than three-quarters of the participants lost an average of 10 pounds during the pilot, helping to save the company about $600,000."
But that is not exactly what the study showed.
The genetic test of Newtopia analyzes "three specific weight-related genes that were chosen based on the strength of scientific research to date. The genes that are analyzed are the body fat gene, the appetite gene, and the behavior (or reward) gene." By their scientific notation, these are the FTO, MC4R and DRD2 genes. FTO and MC4R are indeed among the more than 150+ genetic variants that are robustly associated with weight-related traits, but the evidence for DRD2 is equivocal.
Newtopia's website does not disclose the rationale for selecting DRD2, but the publication of the Aetna study does give a scientific reference: It cites a Nature Neuroscience article with the title, "Dopamine D2 receptors in addiction-like reward dysfunction and compulsive eating in obese rats [italics added]." Oops.
Like most companies in the business, Newtopia does not publicly share how it uses genetic information to personalize weight loss. The Wall Street Journal article writes that "the company would advise more high-intensity exercise for a person whose 'body fat' gene suggests they are likely to retain fat" and that Holly Savage, who "carried two genetic variations that make her more prone to holding weight [and] one variation of the 'appetite' MC4R gene, which affects signals telling the body it is full" was advised to "cut back on habit-forming foods such as sugar." She had also "taken up running because her gene test suggested she requires more vigorous exercise to lose weight."
But why does a person with genetic variants in the body fat gene need high-intensity exercise? And how much? How much better is high-intensity exercise compared to alternatives? And what is the optimal wellness program for combinations of the variants in the three genes? How does the company know what works best for specific genetic profiles? Ideally, that is the evidence that is needed to claim that the program is based on science.
But there are no published scientific studies that provide this evidence, and also the Aetna study did not investigate which wellness strategy works best for people with different genetic profiles. Aetna investigated whether, overall, a personalized wellness program provides health and financial benefits without disclosing how programs were optimized for individual participants.
The Aetna study showed that participants on average lost 10 pounds, but surprisingly, it did not show whether the weight loss was different between people who received the wellness program and those who didn't. There were only minor differences between the groups for some health outcomes such as cholesterol level and waist circumference, but not for all. And while Aetna believes that the program helps save money, this did not follow from its study.
The study showed substantial differences in health care costs between people who joined the program and those who didn't (which is miraculous for a wellness program that had no clear health benefits), but this comparison does not prove that the program saves money: There may have been differences in health care use between the two groups before the start of the study. The researchers should have compared the medical costs of participants before and after they completed the wellness program to see whether the program made a difference.
The Aetna study fits in a tradition of poorly reported, and potentially poorly conducted, scientific studies that aim to provide the scientific basis of genetically personalized wellness programs. So far, these studies have failed to do so. While personalized programs can have personal utility, as demonstrated by the testimonials, the benefits of such programs might be limited to those who believe in them.
If someone tells me that people with red hair have much trouble losing weight, I am eager to believe that: I have red hair and trouble losing weight, and, after many failed attempts, I would welcome an explanation for the failed weight loss that is outside my personal control. If they tell me that, for best results, I should replace my bad eating habits with hair color-matched vegetables, such as tomatoes, carrots and red bell peppers, my extra pounds will fade away. At least for a while.
That is how a genetically personalized diet works.
Is there anything wrong with that?
But it is nonsense.