A new study appears to raise questions about the value of low-fat diets and comes as rather a blow after years of diet and health advice on the benefits of eating less fat and eating more fruits and veggies.
This regime supposedly offered rewards in terms of preventing everything from heart disease to cancer.
The new study, a part of the Women's Health Initiative, the Randomized Controlled Dietary Modification Trial, looked at a total of 48,835 women.
The hypothesis that a low-fat dietary pattern can reduce breast cancer risk has existed for decades but has never been tested in a controlled intervention trial.
The trial aimed, over an 8 year period, to compare women eating normal diets with women asked to eat less fat and more fruits and vegetables.
The researchers found that among postmenopausal women, a low-fat dietary pattern failed to show a significant reduction in invasive breast cancer risk.
It was also seen that a reduced total fat intake and increased intakes of vegetables, fruits, and grains did not significantly reduce the risk of CHD, stroke, or CVD in postmenopausal women and achieved only modest effects on CVD risk factors.
Neither did it reduce the risk of colorectal cancer in postmenopausal women.
The researchers suggest that diet and lifestyle interventions may be needed to improve many risk factors.
In the event it seems the two groups had little difference in diet and while those with "healthier" diets cut calories from fat by only 8.2% compared with the normal group and ate only 1.1 additional servings of fruits and vegetables a day, the difference was too small for any health benefits to be expected .
Scientists are now aware that the type of fat eaten is more important than the amount.
It is now common knowledge that monounsaturated fats, such as those in olive oil, or omega-3 fats found in fish, are healthier than the type of saturated fat found in butter or beef.
The so-called trans fats, which are created by adding hydrogen to natural fat, are by far the worse offenders and seem to be used in everything under the sun from margarine to cookies.
They have been significantly linked to an increased risk of heart disease.
So what is the general public meant to make of the continuing stream of conflicting advice offered on diet and health?
The overall consensus among experts appears to be that eating a relatively healthy diet, exercising regularly and keeping both mind and body active are the clues to well-being.
The study is published by the Journal of the American Medical Association.