Weight issues are a problem for many people. For those that have weight concerns most are overweight or obese, with a BMI higher than 30 kg/m2, but there are a number of people who also have the concern of being underweight, with a BMI lower than 18.5 kg/m2. It is important to understand how being overweight or underweight affects the diver as there are special concerns when it comes to their safety and ability to perform.
When it comes to a diver being overweight there are a number of concerns. Overall, the question is whether or not the person is fit to dive, a question that should be posed to every would-be diver regardless of weight. However, there are a number of conditions that commonly go hand-in-hand with being overweight, including a higher risk of cardiovascular disease and diabetes, an increase in the risk of getting decompression illness, a decrease in pulmonary function, and a decreased level of physical fitness. This is a lot to consider when it comes to diving as there is a lot more risk underwater than for any land-based sport.
Let's look at the issues one at a time. Overweight people have a higher risk of cardiovascular disease and diabetes. This is bad in and of itself, but when it comes to diving the presence of these diseases can spell disaster for the diver, particularly if the condition has not been detected. Cardiovascular disease can mean an increased risk of a cardiovascular event happening while the diver is submerged. When it comes to diabetes, a diver has a higher risk of either drowning or having an arterial gas embolism during their ascent.
What about decompression illness? Well, this condition is brought on when nitrogen gas becomes trapped in the tissues of the body. Nitrogen dissolves readily in fatty tissue, otherwise known as adipose, and since there is a higher proportion of fatty tissue in overweight people, these people can have a higher amount of nitrogen enter their fatty tissue while diving. This can cause a large number of gas bubbles to form on ascent and, while this would not cause any pain, these gas bubbles could enter into the bloodstream and would be carried to the heart and lungs, potentially leading to an embolism in the brain.
Aside from the health concerns discussed above, overweight people generally have a lower lung capacity and a lower level of overall physical fitness. This decreased pulmonary function can cause an overweight diver to be at risk for carbon dioxide retention and hypoxia as all parameters of pulmonary function would be negatively affected. When it comes to a decreased level of physical fitness, overweight divers may not be able to handle situations in which a large amount of physical effort is required. This includes situations such as strong currents and emergencies. The inability to perform a self-rescue or help a dive buddy can lead to injury and death.
There is very little information available when it comes to underweight divers. However, the greatest concern in this situation would be the presence of an underlying health problem that would be causing the low BMI. The person may be bulimic or anorexic or might have an undiagnosed illness. These conditions may make diving unsafe and if a person is underweight, then it is important to consult with a physician before diving. The ability to physically handle the gear and diving conditions, which may be strenuous at times, must also be considered. As long as there is no underlying health concern and the person is otherwise physically fit, scuba diving is safe.
As you can see, the main issue with weight surrounds those divers who are overweight. When it comes to measuring BMI it is important to take into consideration the amount of fat that a person carries. Some people are of an extremely large build and are very muscular and this rather than the presence of fat, may account for their increased weight. In these cases, the person is not to be considered overweight and can dive safely provided there are no other health concerns. People who have a high BMI, but low body fat and are healthy are also perfectly fine to dive. These BMI guidelines apply to both men and women and the level of overall health and physical fitness should be of prime consideration to ensure that you and those around you experience a safe and enjoyable diving experience.