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Website home>Newsletters>September 2008>Obesity & Diving

Dive The World Newsletter

Are you too fat to dive? What those extra kilos mean...

With not just many North Americans, but also Australians and most other nations, being more obese than ever before in our history, much attention has been given to the obese state of the human race and how it effects our daily, land-based lives.

In this month's Newsletter, Dive The World ponders the impact on those underwater lovers among us who carry around a little bit more than just a few extra kilos.

How does obesity affect our diving enjoyment and what is the impact on the health of the obese diver?

Why do we have fat?

We are born with fat, because as immobile bundles of joy we are not in control of regulating the temperature of our environment and we can't feed ourselves. Fat is our ready source of energy and heat and as babies we store it with glee.

The role of fat in the adult body is largely similar, although by now we've gained a measure of control over our environment (clothing and shelter) and food intake. But fat remains our built-in energy store and insulator, although we need less of it.

Fat builds up when the calories from the food that we eat doesn't get used. It is stored for later use, first in the liver and muscles as a complex carbohydrate, and everything extra as fat. When the body requires it, energy is first sourced from the liver and the muscles, and if demand exceeds supply from these 2 areas, the fat stores are accessed and used for energy.

So why are obese people obese?

If you earn more money than you can spend, you end up padding your savings account. Similarly, if you eat more calories than you burn, you will pad your fat stores with saved up calories.

I guess we can lay some blame on society. On the intake side pushing down the scale, we have fast food (a Big Mac has 530 calories), soft drinks (150 calories in a can of Coke), candy (295 calories in a 65g Mars Bar) and processed foods with high sugar contents contributing to massive calorie intakes.

On the other end we have high living with flat screen TVs, computer-based jobs, transport taking us door to door and a general 'sit back and relax' attitude - encouraging sedentary lifestyles and burning little more than the approximately 1,200 calories per day it takes to keep our bodies alive.

In short, a vast increase in calorie intake, and a decline in calorie burning activities, equals huge stores, a.k.a. FAT.

Obesity and Diving - are there any advantages?

Surprisingly, yes.

Fat, as any whale, dugong or seal could tell you, is a great insulator and thus keeps a diver warm. However, for us humans not living in the freezing waters of the world's oceans, muscle insulates just as well in a resting state and generates heat in an active state so, kilo for kilo, muscle is better for you than fat.

Next, fat people are strong. Underneath the flabby exterior there are muscles hard at work to move all that extra body weight. Also, the added pressure on the bones increases bone density, which means stronger bones. Of course, a few hours per week in the gym lifting weights would net you the same, but healthier, result.

Lastly, and perhaps it's not as much a benefit as much as it is a virtue of the sport, diving is excellent for heavy individuals, as there's no impact on joints, plus the water supports excess weight, creating an illusion of light-footedness whilst underwater.

But the disadvantages are many...

To the obese, diving could quickly turn into an exerting activity. To start with, fat is less dense than water, so the obese person is already more buoyant than the average diver. Add to that the larger required wet suit, which if it's made of neoprene means even more buoyancy.

For the suited up obese diver to achieve neutral buoyancy, a large amount of lead is required, which means a pretty heavy weight belt. Also keep in mind an ample girth equals more drag in the water, so more energy is required to move the same distance as non-obese divers.

The increased weight and effort will translate into a higher requirement of air, so for a decent bottom time, a large air tank will be required.

The fully kitted diver is now really heavy and bulky. Not only will it be difficult to get in and out of the water, but should the diver get into trouble, they will really get into trouble, because other divers will have difficulty assisting.


Then of course there's the question of Decompression Sickness (DCS) and whether or not obese divers are at greater risk than others.

When saturated, fat stores 5 times as much nitrogen as water, which seems alarming at first glance, but luckily fat suffers poor blood circulation (or not so lucky, it causes orange peel skin). Thus, on a run-of-the-mill dive not too much nitrogen will make it into the fat.

However, if over several consecutive days multiple dives were undertaken, fatty tissue might well absorb enough nitrogen to increase the risk of DCS. This, however, is but a small slice of the obese diver's risk pie.

An obese diver is in fact more likely to suffer DCS due to the extra nitrogen they absorb as a result of working so much harder under water.

Overheating is also a real danger, as are the other things the disclaimer form warns us against, including increased risk of heart attack or stroke, higher likelihood of diabetes and its associated blood sugar issues, and frequent joint problems - all exaggerated by an overweight state and things that can turn a nice dive nasty.

Fat chance

All said, obesity isn't healthy, whether you're wet or dry.

We know about the challenges and risks the obese face on land and it's clear that underwater, life doesn't get that much easier. An obese diver is likely to have a more strenuous and less enjoyable dive, quite in contrast to what many like about diving.

So eat healthy, stay active and let's Dive The World!

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