An Important Study and The Null Hypothesis


Exciting growth chart examples are forthcoming, but this is an important scientific study which we should discuss.

If you have been following health news lately, you have seen press releases on the “Look Ahead Trial.” This is a fairly well designed study. It looks at diet, weight loss and followup health benefits in Type 2 Diabetics. The patients were followed for as long as 11 years before the NIH halted the study because they noted there was NO difference between the treatment group and the control group with regards to cardiovascular (CV) events such as heart attacks and strokes. The treatment group was given a specific dietary/exercise plan of action. The control group was told to do whatever they wanted. The treatment group, indeed, successfully lost weight, but as mentioned above, there was no difference in CV events. We will get into the diet intervention later in the post.

After stopping the study, many news outlets screamed the headlines. “Weight loss doesn’t work!!!!.” I’m paraphrasing. Here are some examples: here, here, and here.

“Dr. Hoop, what’s the point of weight loss than?” or “Dr. Hoop, why should I even bother to eat right?”

Let’s dig a little deeper and I will tell you more about the Look Ahead study. By the way, the study cost $220 million dollars. Even though there was no significant difference between groups regarding CV Events, it still gives us valuable information.

Why? First, let’s talk about the “Null Hypothesis.” ANY SCIENTIST WHO KNOWS WHAT HE/SHE/THEY ARE DOING CAN TELL YOU ALL ABOUT THE NULL HYPOTHESIS (again, not yelling, just emphasizing). Here is the wikipedia definition for the Null Hypothesis: “The practice of science involves formulating and testing hypotheses, assertions that are capable of being proven false using a test of observed data. The null hypothesis typically corresponds to a general or default position. For example, the null hypothesis might be that there is no relationship between two measured phenomena or that a potential treatment has no effect.” In other words, the Null Hypothesis states there is no relationship between Event A and Event B. Event A does not cause Event B and Event B does not cause Event A. When a scientist goes about trying to prove a theory, HE/SHE /THEY ARE TRYING TO REJECT THE NULL HYPOTHESIS. From a mental standpoint, a good scientist will approach a given theory by trying to prove it wrong (try to support the Null Hypothesis) – “How could this be proven wrong?”

Remember what Gary Taubes says in Good Calories Bad Calories. “A sound theory,” referring to the words of the great 18th century genius Sir Francis Bacon, “gains strength over time and welcomes a challenge whereas a weak theory has to try harder and harder to find supporting data and will tend to omit, dismiss, even ignore data that contradicts it and with time becomes more and more frustrated. A clear sign of a failing theory,” says Taubes, “Is how increasingly sensitive to criticism it becomes and how easily it can regress into hypersensitive, protective dogma.” Taubes concludes that “This is exactly what has happened in diet and health science. It has betrayed the fundamental imperative – to be rigorously self-corrective.”

“Dr. Hoop, please move on to the study.” Will do.

So if you read the majority of press releases or blog posts regarding the Look Ahead study, you would come away with the impression that “weight loss, regardless of the method used” (Event A) has no bearing on “cardiovascular events such as heart attack and stroke” (Event B). It would appear that the Null Hypothesis is supported. I would agree that it is, but in what way? What exactly is “Event A”?

Let’s look at the Look Ahead study protocol (pun intended). It is located as a PDF file at the Look Ahead website. Remember, there are many ways to LOSE Weight (ex. LCHF, starvation, etc.) To find out more specifically what weight loss intervention was used, you can look at Page 35 of the PDF:

“5.4.5 Diet Restriction of caloric intake is the primary method of achieving weight loss. In order to aim for a weight loss of 10% of initial weight, the calorie goals are 1200-1500 kcal/day for individuals weighing 250 lbs (114 kg) or less at baseline and 1500-1800 kcal/day for individuals who weigh more than 250 lbs. These goals can be reduced to 1000-1200 kcal/day and 1200-1500 kcal/day, respectively, if participants do not lose weight satisfactorily. These calorie levels should promote a weight loss of approximately one to two lbs/week. The composition of the diet is structured to enhance glycemic control and to minimize cardiovascular risk factors. The recommended diet is based on guidelines of the ADA and National Cholesterol Education program and includes a maximum of 30% of total calories from total fat, a maximum of 10% of total calories from saturated fat, and a minimum of 15% of total calories from protein. During the first four weeks of the intervention, participants are encouraged to follow a portion controlled diet, given findings that this approach produces significantly larger weight losses than having participants consume a self-selected diet of conventional foods.”

We now know that calories were consciously counted and that portions were consciously controlled. If you’ve read my blog or have followed other quality low carbohydrate blogs, you know this is a failed method. You know that this (along with the low fat theory) has been the prevailing theory regarding both obesity and CV disease for decades. Regarding dietary composition, the diet was restricted in terms of total fat – 30% (there was no restriction on omega 6 polyunsaturated fatty acids or PUFA-rich vegetable oils! I have not discussed omega 6 PUFA-rich vegetable oil in detail yet but they are terrible for you – a science supported statement). In the study, calories consisting of normal dietary saturated fat (the healthy fat) were restricted to 10%. Patients were allowed a minimum of 15% protein. Although it was not explicitly stated, this means that the patients were allowed up to 55% carbohydrate – from any source.

Remember, that LCHF does not limit protein and normal dietary saturated fat. It may also help to remember that a REAL low carbohydrate diet starts at 10% carbohydrate (ideally from non-sugar and non-grain sources – such as fruits and vegetables). LCHF prohibits PUFA-rich vegetable oil. Also, remember LCHF naturally controls portions through hormonal feedback. Most notably Leptin. Finally, we know that all controlled weight-loss trials utilizing a (REAL) low carbohydrate diet conclude superior results.

So instead of saying there was no measurable benefit (or the Null Hypothesis was supported) from “weight loss in general” with regards to “CV events” as the headlines are screaming, they should be saying something different. They should be saying something along the lines of “weight loss resulting from a low-fat, omega 6 PUFA-rich vegetable oil abundant, conscious calorie restricted, conscious portion controlled diet plus exercise” appears to fail in preventing “CV events.”

Maybe we can finally put the “low fat, consciously portion/calorie controlled” theory behind us. That would certainly make this pediatrician happy :-). Our children certainly deserve it! Go science!


  1. Well said Dr. Hoop. You should have also quoted what followed your original quote: “…Look AHEAD investigators initially were concerned that the high sugar content of some meal replacement products might adversely affect glycemic control.”

    They’re having diabetics sugar bomb themselves by downing Slim Fast shakes instead of real food… then they’re surprised when CVD risk doesn’t decrease!

    • Yes, thank you. Giving refined carbohydrate (sugar, hfcs, wheat, etc) – in large quantities – to Type 2 diabetics (or anyone for that matter) is counterintuitive. The evolving understanding of CV disease as a blood sugar and inflammatory problem (insulin being an inflammatory hormone) would explain the lack of improvement in CV risk in the intervention group.

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