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For decades, nutritionists and scientists have been debating whether weight loss is down to sheer will power and healthiness of diet, or whether maintaining a healthy weight is down to your genes.
Now, researchers at the Australian National Phenome Centre (ANPC) at Murdoch University and partners at Imperial College London have shown that people react differently to being fed exactly the same diet.
Further, in an article in Nature Food, they say that for different people, urine contains different patterns of chemicals suggesting that we each have a unique response to diet.
ANPC director Prof Jeremy Nicholson said even when everyone consumed the same amount of calories, some people excreted more calories in their urine than others.
The interaction between our genes and environment is complex and understanding the relationship between our metabolic response to diet is key to the prevention of chronic conditions such as obesity, heart disease and diabetes, Prof Nicholson, who is also pro vice chancellor of Murdoch University’s Health Futures Institute, said.
As part of the research, a group of healthy individuals were given four different diets ranging from a healthy diet, containing lots of fruit, vegetables and fibre, to the equivalent of a fast food diet and their metabolism was measured.
"Some individuals were more responsive to diet than others, regardless of whether the diet was healthy or not," Prof Nicholson said.
The metabolic pathways that were activated after each diet were found to be different between people, these differences relating to blood glucose levels.
Several of the chemicals that changed in the urine were generated by gut bacteria, which is consistent with the fact that people have different gut bacteria and that these bacteria can use different foods as fuel.
Premier’s Fellow and professor of computational medicine at Murdoch University Prof Elaine Holmes said understanding how the bacteria are impacted by diet at the individual level will help to develop new dietary strategies for maintaining health.
"Based on the metabolic response to the four different diets, we were able to create a model that can predict the healthiness of a person’s diet," Prof Holmes said.
"We tested the model in two different populations and compared the chemical profiles to dietary records.
"This model will provide a framework for developing precision nutrition programmes aimed at healthy weight loss or maintenance."
Dr Isabel Garcia-Perez from the department of metabolism, digestion and reproduction at Imperial College London said they were in the process of implementing the tool in dietitian clinics to improve the nutritional management of patients, which would make a real difference.
Prof Gary Frost, the head of nutrition research at Imperial College said it was the first time they had tools to rapidly evaluate the diet-microbiome interactions that affect individual responses to complex diet patterns in the real wood.
Prof Nicholson said given the global importance of both over and under-nutrition in driving chronic disease, any new method that helps to understand response to diet at the individual or population level could be a valuable healthcare tool.