The research also correlated higher BMI with higher sugar intake.
Researcher Malin Haglund Garemo, a dietician from Gothenburg University in Sweden, said that more studies are planned to investigate if obesity was being caused by an early increase in insulin, and not fat.
"Such results would go against the common perception that fat causes increased insulin production as a result of insulin resistance," she said.
The rate of childhood obesity is set to double by the end of the decade, according to recent forecasts by the International Obesity Task Force (IOTF). The alarming figures on childhood obesity estimate that by 2010 almost 287 million kids will be obese, and the overall obese population could rise to 700 million by 2015.
Garemos dissertation study focussed on 182 healthy four-year-olds in Gothenburg and examined eating habits and lifestyles. Twenty per cent of the children were classified as being overweight based on their body mass index (BMI greater than 25 kg per sq. m and less than 30 kg sq. m), and two per cent were obese (BMI greater than 3030 kg sq. m).
"Most of the children in our study come from good socioeconomic backgrounds. If the study had reflected all four-year-olds in Sweden, more children would probably have been overweight," said Haglund Garemo.
Diets, socio-economic, lifestyle and health questionnaires were completed by the parents of the children, and analysis of the children's body build showed that weight increases was a result of the body storing more fat, but those who ate the most fat were not the ones who weighed most. Instead, children who ate less fat had higher BMIs, reports Haglund Garemo.
Startlingly, a fourth of all energy requirements of the children was coming from "junk food" (candy, ice cream, cookies, and sweet beverages), despite the overall energy intakes being in accordance with Nordic nutrition recommendations (NNR 2004).
"Most children had higher intake of saturated fat and sucrose than NNR 2004, while the intake of polyunsaturated fat - especially omega-3 fatty acids, vitamin D and iron were lower than recommended in most children," wrote Haglund Garemo.
"Every third child in the study ate far too little unsaturated fat, above all too little omega-3. These children had significantly higher body weight. This supports other studies that show that obese children have shortages of omega-3," she said.
Haglund Garemo also reported that many of the four-year old girls in the study were already displaying signs of the metabolic syndrome, a condition characterised by central obesity, hypertension, and disturbed glucose and insulin metabolism. The syndrome has been linked to increased risks of both type 2 diabetes and CVD.
Indeed, the research indicated that children with the highest insulin levels gained the most weight since birth.
"Risk factors for the metabolic syndrome can be identified already in healthy 4-year olds, especially in girls," she said.
The Swedish Research Council published the research findings.