So you want to lose a few kilograms. You've heard the mantra: "Eat right. Work out."

But when it comes down to it, which one of those things will make a bigger difference in helping you achieve your weight loss goals? Is it really better to hit the gym four times this week or to order a salad instead of chips at lunch?

We asked Philip Stanforth, a professor of exercise science at the University of Texas and the executive director of the Fitness Institute of Texas, whether diet or fitness was more important for weight loss, and his answer surprised us

"Studies tend to show that in terms of weight loss, diet plays a much bigger role than exercise," said Stanforth.

Here's why: Exercise requires time and consistent effort, and it takes longer to see its results, said Stanforth. It also burns far fewer calories (and takes far more time) than most people think.

Alternatively, there are several high-sugar, high-fat, high-calorie foods that we can cut from our diets to see a pretty big change in our waistline, sometimes in a fairly short time period. Stanforth puts it this way:

"You'd have to walk 35 miles (56 kilometres) to burn 3,500 calories. That's a lot of walking. But if you look at eating, a Snickers bar might have, say, 500 calories. It's going to be a lot easier to cut the Snickers bar than to do 5 miles (8 kilometres) of walking every day." 

(A single Snickers bar is about 220 calories, while a Snickers '2-to-go' is 440.)

Several studies back up Stanforth's suggestion.

One large review of 20 studies involving more than 3,000 people published in the American Journal of Clinical Nutrition in 2014 found that high-protein diets and meal replacements (low-calorie substitutes for heavier meals) were linked with better outcomes in terms of helping people keep weight off after a reduced-calorie diet period when compared with exercise.

And a 2011 review looking at the relationship between fat mass and physical activity in kids concluded that being active is likely not the key determinant in unhealthy weight in children.

Still, exercise may come into play later on. Other studies, for example, suggest that people who lose weight and keep it off eat right and work out regularly.

Plus, exercise has other benefits, from helping to boost our mood and protect our bodies from the detrimental effects of ageing to helping us manage the symptoms of stress, depression, and anxiety. And building and maintaining muscle can often mean your body will actually burn more calories throughout the day.

So if you want to lose weight in 2018, consider adjusting your diet. And if you want to keep it off, get moving.

This article was originally published by Business Insider.