Chris Voigt, the American man who has taken on the challenge of eating only potatoes for 60 days, has admitted he is starting to struggle with the lack of choice.

Now four weeks in, the executive director of the US-based Washington State Potato Commission says he now wishes he set a goal to eat potatoes for only one month.

Voigt has had his potatoes boiled, baked, steamed, grilled, fried, marinated and mashed and he even had one soaked in pickle juice.

Voigt started the diet as part of a PR campaign to prove you can live healthily on potatoes alone.

He committed himself to eating 20 potatoes a day, saying the spuds are rich in potassium, fibre and Vitamin C and have plenty of protein.