Chris Voight, executive director of the Washington Potato Commission, set himself the task of cutting out all other foodstuffs for 60 days to prove the nutritional value of the starchy vegetable.
His challenge was an attempt to prove to the US Government that the potato should remain a part of the school lunch programme, amid claims from the US Institute of Medicine that it should be replaced by other vegetables.
For 60 days, the 45-year-old denied himself all foods except potatoes, seasoning such as salt and pepper, and a little oil to cook them in.
As he ended his trial at midnight on Monday, Mr Voight, denied that the experiment had damaged his health, claiming it had helped him lose 21 pounds and lower his cholesterol.
He told the Today programme: "I absolutely feel great. I've always had lots of good energy on this diet, I've had no strange side effects, I sleep well at night. I just had my last medical exam today and it came back fabulous."
