Twins test out experimental diet

Fat Vs. Sugar: Which Is Worse?
Fat Vs. Sugar: Which Is Worse?

It's fat vs. sugar in the battle for which is worse! Identical twin doctors Chris and Alexander Van Tulleken decided to find out ... using themselves as guinea pigs.

'Alexander could not eat carbohydrates, essentially sugar, and Chris was only allowed a little bit of fat,' 'GMA' reports.

The twins conducted the experiment for an upcoming television program on BBC's 'Horizon.'

The diet lasted for one month. Besides their restrictions, the self-proclaimed gluttons were allowed to eat as much as they wanted and exercise the same amount as usual. So, what happened?

'Both lost weight, but were miserable in the process.'

Alexander wrote about his experience for Daily Mail. He shared that on the no-carb diet he was slow, tired and had terrible breath. He said Chris, on the low-fat diet, was never full and always snacking. Alexander concluded they were going about it all wrong, saying:

'If you want to lose weight it will be much easier if you avoid processed foods made with sugar and fat. These foods affect your brain in a completely different way from natural foods and it's hard for anyone to resist eating too much.'

'Good Morning America' brought on its Chief Medical and Fitness editor who chimed in with a few more tips.

'There's three things you need to do: You need to eat less, you need to eat differently, and you need to use your body more.'

Noted! The twins' special will air Wednesday, January 29th.