IF you're desperate to kick-start your New Year weight-loss mission early, sweet potato could be the secret.
A key protein left behind in the starchy water used to boil the root veg has been found to help blast fat stores in just one month.
The peptide was found to aid slimming in mice - by fuelling the digestion of fat.
And, now scientists hope to see the same results in humans.
They found mice on a high-fat diet had significantly lower body weight after one month, if they were fed sweet potato peptide, which is produced by enzyme digestion of proteins in the water wasted during the cooking process.
They said it suggests the peptide plays a role in digesting fats.
More than 105 million metric tonnes of sweet potato are produced across the world every year, according to the International Potato Center - making it the world's fifth most important crop.
About 15 per cent of sweet potato is used to produce starch materials, processed foods, and distilled spirits in Japan.
The resulting wastewater is typically discarded during the distilling process.
The waste prompted researchers at the National Agriculture and Food Research Organisation in Japan led by Dr Koji Ishiguro, to explore how to use the water.
We were surprised that sweet potato peptide reduced the levels of fat molecules in the mice and that it appears to be involved controlling appetite suppression moleculesDr Koji Ishiguro
Dr Ishiguro said: "We throw out huge volumes of wastewater that contains sweet potato proteins - we hypothesized that these could affect body weight, fat tissue and other factors.
"Finding alternative uses for the sweet potato proteins in wastewater could be good for the environment and industry, and also potentially for health."
The team fed three groups of mice high-fat diets, giving one group the protein digest - sweet potato peptide - at a high concentration and one group at a lower concentration.
After 28 days they weighed the mice and measured their liver mass and fatty tissue.
They also measured the levels of cholesterol and triglyceride fats, as well as leptin - the hormone that controls hunger - and adiponectin, which regulates metabolic syndrome.
Mice given the sweet potato peptide had a lower body weight and liver mass, the researchers found.
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Those fed the peptide also had lower cholesterol and triglycerides and higher levels of the hunger controlling hormone.
The scientists concluded their results suggest the peptide helps to activate appetite suppression and control fat metabolism in mice that are on a high-fat diet.
Dr Ishiguro added: "We were surprised that SPP reduced the levels of fat molecules in the mice and that it appears to be involved controlling appetite suppression molecules.
"These results are very promising, providing new options for using this wastewater instead of discarding it. We hope SPP is used for the functional food material in future."
The findings are published in the journal Heliyon.