The price of fruit has gone up by 34% since 2007. The study found that single parent households experienced a marked reduction in the nutritional quality of their diet.
Pensioners began to choose fatty foods while households with children opted for sugary products. Opting for less healthy processed food is a big cause of worry.
"Over the recession households have responded to higher food prices and the squeezes on their incomes by switching to cheaper calories. This has coincided with a fall in the nutritional quality of foods purchased, with moves away from fresh fruit and vegetables and towards processed foods. As a result, the average saturated fat and sugar content of food purchases has increased over this period," the report author said.
Children's Food Trust chief executive Linda Cregan said: "Feeding children well is absolutely crucial for their future health - these figures are an indication of just how tough this has become for many families in recent years. Some of the trends in this report are a huge worry - we need to see the foods children eat containing less saturated fat, salt and sugar, not more."