Healthy, but overweight!
Consider two questions:
(1) Will an overweight individual suffer any ill health effects by diving? and
(2) Will this individual be able to perform all of the necessary skills to dive successfully?
There is no strong body of evidence to suggest that overweight individuals have a greater risk of DCI or that they suffer more dive-related injuries that divers who are within 10 percent of their ideal body weight. Obesity by itself does not restrict diving.
The best indicator of diving fitness is the individual's general health and level of physical fitness. Keep in mind that divers who are overweight can have a greater risk for cardiac incidents. Consider the exercise regimen - or lack of it - in an overweight individual. Diving requires a diver to lift and carry scuba equipment, swim both underwater and on the surface.
When evaluating a candidate for scuba, a dive physician will consider these factors as well as the "reserve" factor: the increased cardiovascular and respiratory response required when a sudden need arises. In an emergency situation, unfit divers may end up in a near-drowning or fatal dive incident.
The second question considers an individual's ability to perform self-rescue in the open water and assist a buddy. Both skills are vital to the scuba buddy system. Will your partner's physical conditioning and stamina allow him or her to provide assistance to you at the surface?
These are good questions to ask any dive buddy. Remember, it is difficult to get a heavy person out of the water and onto the back of a boat for cardiopulmonary resuscitation (CPR): you can lose vital minutes. Morbidly obese individuals with no exercise tolerance can dive in a tranquil sea: it's when things go wrong or when circumstances change that they have to call upon their reserves.
Fitness for diving depends on more than just one criterion like weight. Physical fitness and ability are major factors to consider. Other experiences in life don't always prepare a new diver for the potential physical exertion he or she can encounter underwater. For some, lacking physical fitness and endurance and being overweight may be a barrier to dive training. Also, divers who have gained weight over the years might now be considered unfit. These divers do have the advantage of experience, however. Perhaps this can help them avoid situations that can stymie new divers.
Each individual is different, and that's the way diving fitness decisions should be made. Individuals who want to learn to dive should join introductory scuba programs through local dive stores: they could see how they handle themselves with equipment in the water. Equally important, they can get the opinion of a professional instructor who can speak realistically about the physical abilities needed for diving.
I am an obese person but I swim at least 1km per day. Most divers who are at their body weight, if they suffer equipment failure is a worst risk than me because most of them can not swim properly. One factor that I did not consider is that it will be more difficult to get me on the boat. However when we did our Rescue course my wife who weight less than 50% of my weight with assistance of our regular Skipper at Sodwana easily got me on the boat for simulating CPR.
Would more mass not necessarily equate to more gas absorption? And in that case a risk leading to minor / micro embolism or dci? IMHO fitness I key to better sac rate and longer dives, whether overweight or underweight. And I know a bunch of people that are very fit even though the are overweight. My question is related gas absorption and whether decompression / off-gassing have to be adjusted to bulk.