Research published in the British Medical Journal showed that people who reduced their fat consumption, without dieting, shifted around three-and-a-half pounds.
The study from the University of East Anglia also revealed that participants who took a healthier approach to meal times kept the weight off for at least seven years.
According to the paper, 73,589 men, women and children were involved in the study, which covered North America, Europe and New Zealand.
Those who ate less fat than usual reduced their body weight by 1.6kg and curbed their waists by 0.5cm, even though weight loss was not the intended outcome.
As such, the study noted that cutting back on fat can lead to weight reduction in people following normal diets.
Dr Lee Hooper, from UAE's Norwich Medical School, observed that the weigh loss in people who ate less fate was "remarkably consistent".
However, this was not a rapid solution to a trimmer physique as the participants were eating a normal amount of food, just with less fat content.
Dr Hooper said: "What surprised us was that they did lose weight, their BMI decreased and their waists became slimmer.
"There isn't a specific goal, the more fat you cut down, the more your weight falls."
As well as shedding pounds, the research noted that a particular reduction in saturated fat consumption is good for cardiovascular health and cutting the risk of cancer.
Dr Hooper suggested a number of healthy eating tips to stay in shape not just over the festive period, but well into the new year and beyond.
She advised swapping full fat dairy products for low-fat alternatives, switching biscuits, crisps and cakes for fruit and trimming the fat off meat.
"Being physically active, not smoking, drinking alcohol in moderation, eating plenty of fruit and vegetables and drinking plenty of fluid also help to keep us healthy," Dr Hooper concluded.