FRIDAY, April 15 (HealthDay News) -- Losing weight can help reduce your risk of cancer if you're overweight or obese, but not all diet plans are effective in lowering that risk, an expert says.

Diets that help protect against cancer are those that encourage long-term changes in eating habits and also provide a variety of options from all food groups, explained Daxaben Amin, a senior clinical dietitian in the clinical nutrition department at the University of Texas M.D. Anderson Cancer Center.

The Mediterranean-style diet promotes a life-long commitment to good nutrition and also meets many of the dietary guidelines for preventing cancer and heart disease, including:

  • Plenty of fruits, vegetables and other plant-based foods.
  • Using herbs and spices to flavor foods instead of salt.
  • Limiting consumption of red meat and alcohol.
  • Using healthy fats such as olive and canola oils instead of butter.
  • Eating fish and poultry at least twice a week.

Another good diet is the whole-body type of diet, which involves eating six to seven small meals a day instead of the usual three large meals. It offers the following cancer prevention benefits:

  • Fruits, vegetables and whole grains in at least half your daily meals.
  • Limiting foods high in fats.
  • Eating lean protein.
  • Daily physical activity.

"Diet plans that encourage short-term change usually don't provide the nutrients your body needs on a daily basis. These diets make our 'bad' list," Amin said in a cancer center news release.

Gluten-free diets are becoming popular but people shouldn't go gluten-free unless they have celiac disease, Amin advised. Going gluten-free means avoiding foods with whole grains, which are high in fiber, vitamins and minerals -- all of which protect cells from damage that can lead to cancer.

Carbohydrate-free diets are another bad choice. Completely eliminating carbohydrates deprives the body of its primary source of energy and of some important cancer-fighting foods -- vegetables, fruits, whole grains and beans.

"Instead of going carb-free, choose your carbohydrates wisely. Pick whole grains rather than cakes, cookies and other foods made with processed or refined grains and sugars," Amin suggested.

More information

The U.S. National Cancer Institute has more about cancer prevention.