NEW YORK — Bacon and black coffee for breakfast, or oatmeal and bananas?

Two major studies last year provided more fuel for a particularly polarizing topic — the role carbs play in making us fat. The studies gave scientists some clues, but, like other nutrition studies, they can’t say which diet — if any — is best for everyone.

Before embarking on a weight loss plan for the new year, here’s a look at some of what was learned last year.

FEWER CARBS, FEWER POUNDS?

It’s no longer called the Atkins Diet, but the low-carb school of dieting has been enjoying a comeback. The idea is that the refined carbohydrates in foods like white bread are quickly converted into sugar in our bodies, leading to energy swings and hunger.

A recent study seems to offer more support for low-carb proponents. But, like many studies, it tried to understand just one sliver of how the body works.

The study, coled by an author of books promoting low-carb diets, looked at whether varying carb levels might affect how the body uses energy. Among 164 participants, it found those on low-carb diets burned more total calories than those on high-carb diets. The study did not say people lost more weight on a low-carb diet — and didn’t try to measure that. Meals and snacks were tightly controlled and continually adjusted so everyone’s weights stayed stable.

Caroline Apovian of Boston University’s School of Medicine said the findings are interesting fodder for the scientific community, but that they shouldn’t be taken as advice for the average person looking to lose weight.

DO I AVOID FAT TO BE SKINNY?

For years people were advised to curb fats, which are found in foods including meat, nuts, eggs, butter and oil. Cutting fat was seen as a way to control weight, since a gram of fat has twice as many calories than the same amount of carbs or protein.

Many say the advice had the opposite effect by inadvertently giving us license to gobble up fat-free cookies, cakes and other foods that were instead full of the refined carbs and sugars now blamed for our wider waistlines.

Nutrition experts gradually moved away from blanket recommendations to limit fats for weight loss. Fats are necessary for absorbing important nutrients and can help us feel full.

SO WHICH IS BETTER?

Another big study this past year found low-carb diets and low-fat diets were about equally as effective for weight loss. Results varied by individual, but after a year, people in both groups shed an average of 12 to 13 pounds.

SO, WHAT WORKS?

In the short term you can probably lose weight by eating only raw foods, or going vegan, or cutting out gluten, or following another diet plan that catches your eye. But what will work for you over the long term is a different question.

Zhaoping Li, director of clinical nutrition division at the University of California, Los Angeles, says there is no single set of guidelines that help everyone lose weight and keep it off.