Water fasting, is it safe?

Tipping the scales at 300 pounds and with triple bypass surgery under his belt, Richard Nall decided to try several rounds of water fasting.

"I just finished a two-week fast during which time I drank nothing but water and coffee and nothing else," said Dieter Richard Nall.

Look online and you can easily find people who drink up anywhere from 24 hours to 30 days. Some nutritionists do not like the liquid plan.

"Any time that we do something like that we risk the, we risk disrupting our metabolism. There's a high chance of rebound weight gain and if people do this for a lengthy amount of time there can be a lot of other health, health risks involved," said Academy of Nutrition Mascha Davis.

Risks like low blood sugar for diabetics, possible electrolyte imbalance or the potential loss of muscle mass if done for an extended amount of time.

Some studies about the potential benefits of fasting in terms of hypertension, arthritis and cancer treatments.

"What I can say is that it seems like there's some exciting findings coming out when it comes to things like cancer or chemotherapy. But in terms of weight management, the long-term studies that I've seen don't support very much benefit," said Davis.

Nall just weighed in at around 220 pounds. He says he is now on blood pressure medication.

"Both my cardiologist who did the surgery on my heart and my general practitioner, who's a brilliant man, verified, validated the water fasting," said Nall.