Weight loss for divers

Text By Dennis Guichard

I thought my medical insurance provider was having a laugh, loading my premiums just because I took up diving. High-risk sport my backside; there’s no ‘high risk’ in scuba diving. I couldn’t think of a lazier and safer way to spend my weekend than drifting along in the current like a southern right whale looking at everything else going about its business over the reef. And then it struck me; it’s not the diving but the southern right shape that’s become me over the years where the issue lays.

If you read the health guidelines for optimised wellness, they recommend at least an hour’s exercise six days a week. I nearly choked on my rusk. I’m a sedentary desk-bound introvert. The most exercise I usually get is the twenty-pace shuffle from my home office to the kitchen for more tea and biscuits. However, I must be honest; that hasn’t done much for my physique. I hope that old-fashioned wit and charm still count for something in the dating game because I’m about all out otherwise. And then I set myself to researching how scuba diving might indeed be my weight-loss golden nugget after all.

I must admit that just the effort of squeezing into an always-too-tight wetsuit isn’t to be scoffed at. It can be a 20-minute wrestle at the best of times, working most muscles in the body and getting my heart rate up. The penguin shuffle to the tractor-trailer for the lift to the beach must chip another few minutes off that daily hour target. Scrumming the dive boat into the surf will surely get my heart pumping if it doesn’t dislodge my knees. The upper body workout holding on for dear life through the surf zone launch is mostly adrenalin and screaming, but I’ll bank what I can. Because beyond that, if I’m fair and honest with myself, there’s not a lot exercise-wise I can bank to trade off against that hearty post-dive breakfast and all the calories that will end up on my waist.
 
Scouting the various diving medicine websites, I was delighted to find a handful of articles that suggest that hyperoxia (high partial pressures of oxygen - ppO2) might, in fact, be beneficial for fat metabolism. A 2016 Swedish research project identified that acute hyperoxic exposure, breathing an oxygen mixture at 31% ppO2, increased physical performance and lipid (fat) oxidation.

Fat oxidation was shown to be increased by a whopping 52% with a corresponding reduction in carbohydrate oxidation. Oxidation is the process by which an energy source (glucose or fats) is combined with oxygen in our cells to produce energy in the form of ATP. Maximum exercise power output also increased by 2.4% in the same study. The topic is nothing really new. You’d already know this, of course, if you’ve read my article in the September 2022 edition of the Alert Diver Lite magazine on ‘Nutrition in Saturation Diving’.

Fat metabolism is the process by which the body breaks down and utilizes fat as an energy source. Fat is stored in adipose tissue (some of us seem to have more of it than others) and intramuscular triglycerides. It can also be derived from dietary intake or cholesterol synthesis. Fat metabolism involves several steps that are regulated by various factors, such as hormones, enzymes, transcription factors, and oxygen availability.

Hyperoxia can affect fat metabolism in different ways, depending on the duration and intensity of exposure, fat tissue type and location, and other stressors or diseases.
Triglycerides, the primary form of stored fat in the body, can be broken down into free fatty acids and glycerol through a process called lipolysis. Free fatty acids can then be used as an energy source by various tissues or organs, including muscles, heart, and liver.

We have to be mindful, of course, of the flip side of breathing high oxygen partial pressure gas mixtures like Nitrox in diving. The relative risk of CNS oxygen toxicity if depth limits are exceeded. Increased oxidative stress from the production of Reactive Oxygen Species (ROS). Impaired mitochondrial function. And also altered hormone regulation and gene expression.
We can compensate for being overweight whilst diving by adding extra weights to our weight belts, of course. We’ll still attain neutral buoyancy, although being the shape of a puffer fish isn’t overly good for streamlining. It’s no wonder I’m often the first one back on the dive boat, having run out of Nitrox. It wouldn’t be bad if only they still gave us lollies after the dive, which they don’t. Life seemed so much better in my youth.

Weight loss isn’t rocket science. Just eat fewer calories than you burn. You can’t out-exercise a bad diet and lose weight unless you’re in a calorie deficit. Eat more vegetables than a vegetarian. Increasing your fibre intake is beneficial for the health of your gut microbiome. Get adequate protein in your diet. Do some exercise (note to self). Eat fewer rusks (another note to self). Get some sunshine on your skin (not too much). Drink lots of water. Fresh air is good for the soul. Fresh sea air is even better.

A 2017 published French study of 37 recreational divers indicated that scuba diving positively influenced the ‘perceived stress scale’ assessed in the subjects. It highlighted the positive improvement in multiple psychological factors.

The benefits of weight loss are endless. Improved cardiovascular health is safer for diving, making our bodies more efficient at nitrogen off-gassing and minimising decompression sickness risk. We get a reduced risk of diabetes and the need to spend weeks and months in a hyperbaric chamber undergoing oxygen therapy treatment. Better joint health. Enhanced respiratory function, which would help extend my bottom times. Improved sleep. Increased energy levels. Enhanced mental well-being. An improved sense of self-worth. And we get to live longer so that we can dive for longer.

Just because science papers are formally published doesn’t, of course, necessitate that they’re true. But I’m not a dive doctor, so that makes me free to float as I choose in the grey zones of wild hypothesis. Diving medicine very often doesn’t stray (I guess for good reason) from the tested and proven. But so very often, the best things in life are found floating on the fringes of it all.

There is so much in sub-sea and hyperbaric medicine that is speculated that just hasn’t been proved through extensive random-controlled double-blind trials. But that doesn’t mean that the hypothesis is unfounded. Haldane’s hypothesis of tissue saturation and desaturation in decompression theory is hypothetical, but we’ve followed that blindly for over some 115 years.
If numerous sources suggest that there might be a benefit to fat metabolism when diving on enriched oxygen (Nitrox) breathing gasses or in elevated oxygen saturation environments, that’s good enough for me. What more reason do we need anyway to get motivated to get out diving as much as we can?

It’s important, of course, to approach weight loss in a balanced and sustainable way. Crash diets or extreme measures can negatively affect your health and well-being. For the life of me, I can’t think of a single negative to getting out diving more often. Raise a fin and give me a hearty Pirate ‘Aargh’ if you’re with me...?