Everyone is on the protein bandwagon; there are thousands of protein shakes, protein powders and protein bars on the shelves, all of them pretty expensive, too. But whole foods are still the best way to get your protein. High quality whey protein powders are okay, too. I drink a whey protein shake every morning and after workouts. But which protein sources are best and why?

Well, the uber-smarties at Harvard University School of Public Health have a few thoughts.

First, they say that animal and vegetable sources have equally good amounts of protein and that the key is what else is in your chosen protein; what they call the whole package.

A 6-ounce broiled porterhouse steak is a great source of protein—about 40 grams worth. But it also delivers about 38 grams of fat, 14 of them saturated. That’s more than 60 percent of the recommended daily intake for saturated fat. The same amount of salmon gives you 34 grams of protein and 18 grams of fat, 4 of them saturated. A cup of cooked lentils has 18 grams of protein, but under 1 gram of fat.”

So the main thing is to look at the fat (and sodium and other less-welcome ingredients) that is in a protein food to decide which ones are best for you. You want to choose lower-fat proteins most of the time and indulge in that porterhouse every now and then, not every Thursday.

Harvard also has some other tips for choosing the best protein sources:

1. Mix it up. Most diets supply enough protein.

Eating a variety of foods will ensure that you get all of the amino acids you need.”

2. Go low on saturated fats.

Beans, fish and poultry provide plenty of protein, without much saturated fat. Steer clear of fatty meats and use whole-milk dairy products sparingly.”

3. Limit red meat and eliminate processed meats.
Eating red meat increases your risks of colon cancer, heart disease and Type 2 diabetes.

Make red meat (beef, pork, lamb) only an occasional part of your diet—no more than two 3-ounce servings a week—if you eat it at all. And skip the processed stuff—bacon, hotdogs, and deli meats—since that’s linked even more strongly to cancer, heart disease, and diabetes risk.”

4. Eat soy in moderation
Soy is a good source of protein,

But if you haven’t grown up eating lots of soy, there’s no reason to go overboard: Two to 4 servings a week is a good target; eating more than that likely won’t offer any health benefits and we can’t be sure that there is no harm.”

5. Balance carbs and proteins.

Cutting back on highly processed carbohydrates and increasing protein improves levels of blood triglycerides and HDL, and so may reduce your chances of having a heart attack, stroke, or other form of cardiovascular disease.”

It’ll also help you to lose weight!

Getting enough protein usually isn’t a problem in the American diet; getting enough quality protein is. So choose wisely and don’t overdo it.