In 2013, when the world's tallest horse — a 20-hand, 2-3/4-inch tall (that's 6 feet, 11 inches) Belgian gelding named Big Jake — weighed in at 2,600 pounds, no one suggested that he should eat less than his daily 10 gallons of oats and a bale and a half of hay.

On the other hand, some dietary adjustments are needed to help the 2 billion people around the world who are overweight.

But with all the debate about what constitutes a healthy diet, it's hard to know where to start.

Let's start with fat. Researchers have found that Americans' total fat consumption has skyrocketed from less than 45 pounds a year in 1950 to almost 75 pounds a year in 2000. That's 305,775 total calories per person per year.

On top of that, a new study in Nature magazine reveals that all that fat consumption tells your body to make more of a peptide called neurotensin (NT)— and NT's job is to boost fat absorption: Fat begets fat.

That's why you need to carefully choose your fats. Good fats can improve your health, and reduce inflammation and insulin resistance. Here’s what you need to do:

1. Eat skinless poultry and omega-3-rich fish like salmon and sea trout. Skip processed meats.

2. Avoid omega-6-loaded vegetable fats, like canola and soy oil, and stick with extra-virgin olive oil (except when high-heat cooking).

3. Enjoy healthy fats in nuts (walnuts are loaded with omega-3s) and avocados — just don't overdo it.