Cookery courses launched by TV chef Jamie Oliver have been praised by scientists for helping people to improve their eating habits.
An independent report has discovered that people who took part in Oliver's Ministry of Food courses increased the amount of fruit and vegetables they ate, halved the number of snacks and became more confident about cooking.
Oliver said the study showed that teaching people to cook "really works and really does make a huge difference".
Nutritionists said the findings, which were published in the Public Health Nutrition journal, showed that people will make healthier food choices if they are helped to improve their cooking skills with a back-to-basics approach.
Oliver launched his Ministry of Food courses in 2008, saying he wanted to help people learn to prepare tasty, nutritious food, whatever their budget, and now has four UK centres.
Nearly 800 people who took part in the eight-week courses at the centre in Leeds Kirkgate Market between 2010 and 2014 were surveyed before and immediately after the course.
Researchers, from the University of Leeds spoke to around 500 of those participants again six months later.
They found that the average number of fruit and vegetable portions eaten daily by the participants increased from 2.7 before the programme to 3.4 immediately afterwards and to 4.1 after six months.
The amount of snacks eaten per day dropped from two before the course to 1.7 immediately afterwards and to 1.1 six months later.
The participants also reported significant gains in their levels of cooking confidence, with men reporting a greater growth in confidence than the women who took part, the researchers said.
Oliver said: "Ministry of Food, for me, has always been about empowering people and giving them the knowledge and the confidence to feed themselves and their families better.
'The beauty of it is that it's all about local people helping other local people to create delicious, fresh, nutritious food that doesn't cost a fortune.
"This important study shows that teaching people to cook really works and really does make a huge difference.
"If only more towns and cities had Ministry of Food Centres."
Janet Cade, professor of nutritional epidemiology at the University of Leeds' School of Food Science and Nutrition, said the study suggested that the Ministry of Food courses encouraged short-term changes in eating habits that could be maintained and improved over a longer period.
She added: "In the UK there has been a decline in cooking skills since the 1950s.
"Home-made meals have been replaced with ready meals and convenience foods.
"This lack of cooking ability, coupled with ready access to high-energy convenience foods, has contributed to an increase in the number of people who are now overweight.
"Our study shows that if you help people improve their cooking skills, using basic ingredients, and their confidence in these skills, then they might make healthier food choices."