Science Based Wellness

I promised you that every item on this website would be backed up by evidence. What does that mean in practical terms?

Evidence vs Proof

Evidence based does not mean “proved beyond reasonable doubt.” It means “the best evidence points in this direction.”

There are some things we can say are proved beyond reasonable doubt. If you stop eating eventually you will die. AIDS is caused by the human immunodeficiency virus. Very few people who are vaccinated against measles go on to get the disease.

But there are many things we cannot – at least not yet - prove beyond reasonable doubt. The best we can do is look at which way the evidence points.

A Case Study – the Link between Type 2 Diabetes and Obesity

Rather than talk in abstract terms let’s examine a specific case, the link between type 2 diabetes and obesity.

Broadly speaking there are two types of diabetes called type 1 and type 2.Type 1 diabetes is an inherited condition. You are born with it. The onset of type 1 diabetes has nothing to do with your weight.

Type 2 diabetes used to be called adult-onset diabetes because it mainly afflicted older adults. However the condition is becoming increasingly prevalent in children. To reflect this reality the name has been changed to type 2 diabetes.

A well-known and generally reliable website, WebMD, has this to say about the link between type 2 diabetes and obesity:

…A new study spells out why Americans suffer more diabetes than ever before: O-B-E-S-I-T-Y.

The Mayo Clinic website is more cautious. Here’s how the doctors at Mayo Clinic put it:

In prediabetes — which can lead to type 2 diabetes — and in type 2 diabetes, your cells become resistant to the action of insulin, and your pancreas is unable to make enough insulin to overcome this resistance. …. Exactly why this happens is uncertain, although excess fat — especially abdominal fat — and inactivity seem to be important factors.

This is a much more cautious statement than the one appearing on the WebMD site.

So there is an “association” between obesity and type 2 diabetes. But association is not causation. The best we can say is that fatties are more likely to be afflicted with type 2 diabetes than people who maintain a healthy weight. However many fatties never get type 2 diabetes and men thin people do.

There are in fact numerous studies that confirm a link between the onset of type 2 diabetes and obesity. One such is a 2005 study published in Diabetes/Metabolism Research and Reviews, (Volume 22 Issue 2, Pages 118 – 125.) The article is titled “Life course determinants of insulin secretion and sensitivity at age 50 years: the Newcastle thousand families study” by Mark Pearce and others. The researchers conclude that adult weight is the most important risk factor for the onset of type 2 diabetes.

You can read a summary of the article on the bio-medicine website.

A more interesting question is this:

If you are fat can you reduce the risk of getting type 2 diabetes by shedding excess pounds?

It’s all very well to say that if you’re fat you’re at increased risk of getting type 2 diabetes. But suppose you are fat. Can you reduce your risk by shedding the excess poundage?

The answer to this question, according to the US National Institutes of Health, is “yes.” Weight loss, especially when combined with increased physical activity, appears to reduce the risk of getting type 2 diabetes or, at the very least, to delay the onset of type 2 diabetes.

And that’s really the best we can say for now. The best evidence suggests that losing excess weight delays and may avert entirely the onset of type 2 diabetes.

There are however some dissenting voices. Perhaps at least some cases of type 2 diabetes are caused by POPs.

POP is an acronym for persistent organic pollutant. According to an article by Duk-Hee Lee and others published in Diabetes Care, it is exposure to POPs rather than obesity that increases the risk of getting type 2 diabetes.

In Conclusion

I have done my best to present the evidence for a link between the onset of type 2 diabetes and obesity objectively. There is evidence but the case is not made beyond all reasonable doubt. You will have to decide whether the evidence is strong enough to satisfy you.

Note that the onset of type 2 diabetes is only one risk factor associated with obesity. There are many risks associated with obesity and for some of them the evidence for a causal link is very strong. Even if you find the evidence for the link between obesity and type 2 diabetes to be unconvincing you may still wish to shed a few pounds if you’re fat.

Rating the Evidence

To re-cap, some things we can prove beyond all reasonable doubt. Others we can only look at where the evidence points. I rate everything on this site on my own, entirely subjective and unscientific “0 – 10″ scale where:

“0″ means no evidence at all

“10″ means “proved beyond all reasonable doubt.” When I rate something as 10 I am asserting that, in my judgement, no reasonable person can doubt that the case has been made.

Note that the rating I give each item reflects nothing more than my subjective opinion.

Here are some sample ratings to give you a feel for my opinions:

• The proper use of condoms greatly reduces the risk of contracting HIV / AIDS. Rating = 10.
• Quitting smoking greatly reduces your risk of getting lung cancer. Rating = 10
• Homeopathic remedies are no more effective than placebos. Rating = 9.5
• Losing excess weight will significantly reduce or delay the onset of type 2 diabetes. Rating = 5

Be aware that in the last rating I am going against the weight of medical opinion. Most doctors think the link between the onset of type 2 diabetes and obesity is very well-established. I don’t really doubt the existence of some link; however I am not sure how significant obesity alone is as a risk factor. I think there may be other factors involved.

Tags: diabetes, evidence, obesity, weight loss

This entry was posted on Monday, April 13th, 2009 at 6:45 pm and is filed under diabetes, obesity, weight loss. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.