Drink water and avoid sugary drinks to help prevent cancer, leading scientists have urged.
The call comes as part of a string of recommendations on health and lifestyle choices, dubbed a "blueprint to beat cancer", published by the World Cancer Research Fund (WCRF).
Preventing obesity forms a significant part of the advice, with being overweight likely to overtake smoking as the "number one risk factor for cancer" within decades, the organisation warned.
There is now strong evidence excessive weight is the cause of at least 12 cancers, five more than when the last WCRF recommendations were published in 2007, the authors said.
The findings of their third report, based on a comprehensive analysis of existing evidence, will be presented at the European Congress on Obesity in Vienna, Austria.
For the first time separate recommendations have been included on limiting consumption of soft drinks - urging people to "drink mostly water and unsweetened drinks" - and processed foods.
People should reduce their consumption of fast food and those high in fat, starches and sugars to help control calorie intake, it states.
The number of new cases of cancer is expected to rise by 58% to 24 million globally by 2035 as more countries adopt "Western" lifestyles, according to the report.
Around 40% of cancers are estimated to be preventable, the authors said.
Their analysis linked obesity or being overweight to 12 cancers, including those affecting the liver, ovary, prostate, stomach, mouth and throat, join bowel, breast, gallbladder, kidney, oesophagus, pancreas and womb.
The report states: "Avoiding tobacco in any form, together with appropriate diet, nutrition and physical activity, and maintaining a healthy weight, have the potential over time to reduce much of the global burden of cancer.
"However, with current trends towards decreased physical activity and increased body fatness, the global burden of cancer can be expected to continue to rise until these issues are addressed, especially given projections of an ageing global population.
"If current trends continue, overweight and obesity are likely to overtake smoking as the number one risk factor for cancer."
Only moderate amounts of red meat should be included in the diet, the guidance states, adding: "Eat little, if any, processed meat."
Having a diet rich in whole grains, vegetables, fruit and beans can help prevent cancer while mothers are encouraged to breastfeed where possible to help reduce their risk of breast cancer.
People should limit alcohol consumption, not use supplements for cancer prevention and try to meet nutritional needs through diet alone, the report authors said.
Dr Giota Mitrou, WCRF's director of research funding and external relations, said there is "very strong evidence for a package of lifestyle behaviours as a blueprint for cancer prevention".
"Our research shows it's unlikely that specific foods or nutrients are important single factors in causing or protecting against cancer," she said.
"Rather, different patterns of diet and physical activity throughout life combine to make you more or less susceptible to cancer."
The panel's key recommendations are:
- Be a healthy weight
- Be physically active
- Eat a diet rich in wholegrains, vegetables, fruit and beans
- Limit consumption of fast foods and other processed foods high in fat, starches or sugars
- Limit consumption of red and processed meat
- Limit consumption of sugar-sweetened drinks
- Limit alcohol consumption
- Do not use supplements for cancer prevention
- For mothers: breastfeed your baby, if you can
- After a cancer diagnosis: follow our recommendations, if you can
Not smoking and avoiding excess sun are also important in reducing cancer risk, researchers said.
Caroline Cerny of the Obesity Health Alliance, a coalition of health organisations, said: "As this report shows, carrying excess weight can increase the risk of cancer.
"It is also linked to other health conditions such as Type 2 diabetes, heart and liver disease plus mental health problems.
"But with one in three children overweight or obese by the age of 11, it's not as simple as telling people to eat less.
"It's clear we need an environment that supports and encourages healthy choices, rather than steering us towards unhealthy options with constant adverts, promotions and offers.
"The Government now has an opportunity to step up and publish a truly world leading obesity plan with strong measures to curb the influence of junk food marketing."