Jessica Villa, independent nutritional consultant for Big Matters, said that by sticking to their recommended calorific intakes, people are likely to maintain a healthy weight.
However, she added that the vast majority of nutritional tips are not relevant and will not help in the quest for weight loss.
"I believe that only ten per cent of research into nutrition is valid - the rest is just money making," said Ms Villa.
"Look at all the different diets and books out there, and how many 'gurus' are making millions at the expense of obesity."
Her comments follow research conducted by the University of California, which looked at the role of potatoes and other vegetables with a high glycaemic index.
The study found that people can include potatoes in their diet and still manage to lose weight.