On her fifth attempt, at age 64, Diana Nyad finally completed the 110.86-mile swim from Cuba to Florida.

She knew exactly what she was in for, having previously encountered dehydration, terrible weather, and stinging box jellyfish that triggered severe cramping and terrible pain.

But in 2015, for the more than 45,000 people in the U.S. who had Roux-en-Y gastric bypass (RNYGB) surgery, the gastrointestinal perils they encountered after the operation were a lot more challenging than they had expected.

That's because until now, researchers hadn't clearly identified the bloating, gas, and food intolerances patients develop as they begin shedding their excess weight.

Researchers writing in the British Journal of Surgery recently revealed that more than 70 percent of RNYGB patients cannot eat high-fat or high-sugar foods or red meats without experiencing gastrointestinal distress.

Those foods are just what you should eliminate from your diet anyway — and after surgery, you're going to hear it big-time from your newly redesigned gut.

So if you’ve gone through RNYGB surgery, congratulations.

If you’re thinking about it, make sure you commit to changing your habits and lifestyle before the procedure.

It'll help you reverse Type 2 diabetes and dodge complications far worse than box jellyfish stings.