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Nutrition and Scuba Diving
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Ideal Weight Calculation   by Steve Halls, MD
Eating for Diving
Helpful Nutrition Links
Body Mass Calculation

Eating for Diving 

As your diving season arrives, it might be a good time to remind everyone about eating for diving. Over my many years of diving, I have had the occasion to learn through trial and (mostly) error, as well as watching others, what it takes to have a pleasant day of diving. What you eat just might make the difference between a good, safe dive and what might be a 'bummer', a trip to the chamber. What follows is my  'fool-proof' list of things to eat or drink in preparation for your long-awaited dive trip. 

Six to three days before

This is the time to build your water and carbohydrate stores. Note the order of importance. It is a must to drink enough water so that your urine is 'copious and clear' the last few days before a dive. Being well-hydrated is thought by many to be vital to the prevention of decompression sickness. Excessive alcohol intake or a bout of local "Montezuma's Revenge" will dehydrate one rapidly, and it might take a day or two to recover from becoming dehydrated.

Be sure to choose a good portion of your foods from the bread/starch and fruit categories. Roughly one-half to two-thirds of your calories should be from complex carbohydrates (whole grains, pasta, veggies, fruit, etc.) depending on the intensity of your diving. If you're doing a full week of repetitive dives, stay closer to the  two-thirds calories from carbs and eat plenty of calories. Also, make sure you get enough protein by taking in low-fat dairy products, beans, nuts (use for salads and cooking) soy products, and lean  meat and fish. 

Two days before

This is the day to be sure you have plenty of water in your system and plenty of calories. It's here that some people get into trouble on long airplane trips by ingesting too much alcohol containing beverages. The alcohol acts as a diuretic, directly causing dehydration. In addition, the dry atmosphere of the airplane cabin can cause significant fluid loss.

Most  people do well to eat a little more than usual on this day, sticking to high carbohydrate foods and evenly spaced meals. Some people prefer to get the extra calories from food while others like sports drinks or milk. Also, work on getting a few good nights sleep here, because it can be difficult to sleep restfully on a plane trip to the dive site. 

Day before

Here is where most divers get into trouble--overeating during the trip to the dive site. Avoid bad eating habits you may slip into if you have to travel to the dive. Eating a little less than usual today will make you a little lighter tomorrow on your dive day, so drop your intake by about 500 calories. One of the worst things you can do is raid the pre-dive pasta bash. Lots of oil-laced pasta, buttered bread, and high-fat salad dressing will only give you plenty of "ammo" for the boat head in  the morning. At this point, it's too late to make up for poor eating earlier in the week. Diarrhea on a diveboat is not a good thing! Stick with broth-based soup, Jello, cereal, low-fat pudding, fruit, vegetables, carnation instant breakfast, and sports drinks on this day. Be sure to drink a little extra water. 

Dive day

Stay away from unusual foods. Eat a small breakfast if you suffer from heartburn (gastroesophageal reflux). Be sure to eat at least two hours before the dive and avoid high-fat muffins, doughnuts, and honey buns. If the dive is in the afternoon, keep the portions small and choose high-carbohydrate foods and sports drinks or water for lunch. You should be drinking water up to one-half hour before the dive. About 10 or 15 minutes before the  have a water bottle handy and take in two-four ounces of water. Water consumed this close to the dive start will help counteract the obligatory diuresis of your initial water immersion

During the dive

Depending on the number of dives, drinking water is usually best. Most dive boats have a supply of cold water available with plenty of cups. If it's a long way to and from dive sites with a long off-gassing between dive period, consider a sports drink or try easy to eat, high-carbohydrate foods (fig bars, bananas, sports bars/gels, low-fat cookies, etc.) and plenty of liquids. Most divers bring their own sources of energy (lemon drops, hard candy, oranges). I've not seen any divers using any of the 'sports gels' that runners use. One word of caution--on some dive sites in distant, ethnic spots, the food served for the between dive lunches is indigestible if not inedible. 

After the dive

Scarf down high-carbohydrate foods after a dive as soon as possible (this doesn't include beer if you're diving the next day). Try to eat something every couple of hours all day long if you're diving again and at least for four-six hours after short dives. Avoid alcohol as long as possible the few hours after a dive as it will dehydrate you as well as slow the restoration process of your liver and exercising muscles.

While following these tips may not allow you to dive any deeper or use less air, it can make a big difference how you feel during and after the dives.  It is just possible that you might ward off getting bent and ruining a good vacation or even having  permanent neurological damage. In addition, your slim physique also might also save a few bucks by you being able to get into last years wet suit and BC.


Eating and Flatus
Article about diving and intestinal gas


Diving with intestinal gas can be an experience that most of us would rather not even think of--much less have to deal with.The gas has to conform to Boyle's law and can cause extreme discomfort in ascending from depth--particularly if it has become trapped or increased in amount from whatever source.

Gas is the production of digestion, and most of us pass (fart, poot, bubble) somewhere between 200 and 2,000 ml of gas per day (average, about 600 ml) in roughly 13-14 passages. There was a paper in 1976 reporting a patient who passed gas 34 times in one twenty-four hour period. These emissions are composed of five gases: nitrogen (N2), oxygen (O2), carbon dioxide (CO2), hydrogen (H2), and methane (CH4). Nitrogen usually predominates, followed by variable concentrations of carbon dioxide, hydrogen, and methane, and very low levels of oxygen.

Gas also gets into our guts by air swallowing (which accounts for very little in the lower portions), production within the bowel and colon (which accounts for a lot), and diffusion from the blood. Most air that is swallowed comes out the way it went in: it is belched or "eructed," and in divers this can distend the stomach to the bursting point. Most of the nitrogen is accounted for by diffusion from blood to bowel; it may give flatus some of its bang but little of its bite. I'm not aware that this N2 has any relationship decompression sickness.

The function of the digestive process is to break the presented food into small essential nutrients, which then pass through the bowel wall (absorption) into the blood stream for transportation (distribution) to the various locations where they are used for either the work (metabolism) or construction/repair (anabolism) of the body. Nutrients not needed immediately are stored as fat or glycogen for future use.

Bacteria in the bowel account for 50- 60 % of the gas in flatus --most from the breakdown of carbohydrates, with the production of CO2, hydrogen and methane, often a function of fermentation.

Gas is basically produced by foods that have undigestible or excess carbohydrates, which are not absorbed when they get to the colon. Beans, for example, have complex carbohydrates that are maldigested. And the same holds true for mushrooms, cabbages and onions. Many people don't realize that mushrooms contain a unique sugar called raffinose, which humans can't break down. As a group, vegetarians produce more gas than meat-eaters because the intestinal enzymes can't digest the cellulose in vegetables' cell walls. However, this is where the colon's bacteria come in: the outcome being a marked increase in gas production. "Beano"is the answer to this problem for those of us that have these "carbohydrate eating" bacteria. A few Beano drops will close down this flatus-factory and tablets exist for the more self-conscious restaurant diner.

The amount and odor of flatus are largely accounted for by the type of bacteria we have in our guts. Newborn infants and germ-free rats have no intestinal bacteria, although the infants acquire them almost immediately. And it appears as if the kind of bacteria you acquire in your neonatal life basically persist with you.

The reason this is important is that different bacteria digest different kinds of carbohydrates. Some make more methane; others help hydrogen to combine with sulfur (from other foods or water) to make hydrogen sulfide. It is the latter that have the odor of rotten eggs and the former that have the "flamethrower" reputation with college kids!

Altering this gas response with medications seems to work only part of the time--part of the problem being that some individuals have more intestinal spasm in response to less gas. Anticholinergic medications work for these spastic gut divers.

Additionally we can eat slowly, chew thoroughly, sip rather than gulp liquids, minimize fizzy beverages, not chew gum, and eliminate sugar-free foods containing sorbitol or xylitol -- both are poorly digested and serve up a potent fare for our gas-forming bacterial friends.

If you must eat beans--boil them for three minutes, soak overnight and throw out the water containing the offending carbohydrates. Use of the enzyme "epazote" can also be helpful.

The same advice is good for those who complain of frequent or excessive flatus. If much of the excreted gas is composed of hydrogen and carbon dioxide, which originate in the body, not the air, the problem may be a general malabsorption disorder or difficulty with particular foods. A low carbohydrate diet will often turn down the flatus volume.

In addition to the beans, mushrooms, onions, celery, and other foods containing complex carbohydrates and undigestible fiber, many patients with abdominal complaints also benefit from reducing their intake of lactose, the milk sugar in dairy products. This sugar can cause gas, cramps and diarrhea as can the sorbitol in diet foods like candy, chewing gum, and sugar-free lozenges. Sorbitol is another non-digestible carbohydrate; but, because of its form, people have a harder time making the association between consumption and later discomfort.

Hopefully, this will help explain those cramps in your gut and the terrible odor that your buddy has on those occasions that you both have had black bean soup. Keeping your diet in mind when preparing for a dive just might turn you trip around.


Helpful Nutrition Links

Activity List (calories burned)
Nutrition and Diet Information
Fitness, Nutrition and Your Health


Another Body Mass Calculator
Body Mass Calculation (Steven Halls, MD)

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