Protein

There are a lot of protein sources you can eat during the Core Phase, but you can't eat just any old protein food. The most important thing is to limit the amount of fat you get with your protein. Meat must be lean, and even then you'll need to trim all visible fat before cooking it. Some low-fat or fat-free dairy sources are also allowed.

Allowed Proteins

You can eat any of the following ten protein sources. Some have limitations, so be sure to read the descriptions.

1. Protein shake. You can mix up a serving of protein powder one to three times a day as desired (having one a day can actually be quite helpful). Protein shakes ideally should have at least 20 grams of protein, less than 130 calories, no more than 2 grams of fat, and no more than 2 grams of carbs. Many protein drinks and powders on the market don't meet these requirements and are often packed with carbs. Read the labels closely, and do not use them if they do not comply.
2. Veal and Beef. Be careful here. Low-grade veal is your best choice because it has less fat than beef. For beef (whole cuts or ground beef) look for extra lean beef labeled as 95% lean (or better). Most American beef is typically heavily marbled with fat that's impossible to remove. Range-fed beef is an especially good choice since it's much leaner than regular grain-fed beef.
3. Buffalo or bison. Bison meat, as it's properly called, has been shown to have significantly less fat and fewer calories while containing more protein and nutrients.
4. Chicken. Get skinless, boneless breast meat.
5. Turkey. Get skinless, boneless breast meat.
6. Fish. Any low-fat fish, which is typically white-fleshed. Contrary to some, not all fish is equally healthy, and some fish contains too much fat for the Core Phase diet. The approved list includes albacore tuna, cod, crab, crayfish, flounder, grouper, haddock, halibut, lobster, orange roughey, shrimp, snapper, sole, striped bass, tilapia, and turbot.
7. Beef jerky. Many types of beef jerky can be eaten during the Core Phase, but check the labels and avoid those with extra carbohydrates (sugar) and fat. Beef jerky makes a great snack to help keep hunger away in between meals.
8. Egg whites. No yolks allowed except during your Flex Meals (see below). You can add interest to your egg whites with fat free cheese and all sorts of spices (see below), along with vegetables and other seasonings.
9. Low-fat cottage cheese*. Make sure it's low-fat or fat free. It will still have a few more carbohydrates than we'd ideally like, so don't overdo it.
10. Fat free cheese*. Regular cheese is loaded with fat that will stall your weight loss, and even low-fat cheese has too much. (Don't ask us why low-fat cheese has more fat than low-fat cottage cheese; that's up to the manufacturers!) So any cheese you eat must be fat-free, not just low-fat.

* Note: Calcium can help increase fat loss (and bone health), so if you can it's a good idea to aim for 1 - 3 servings daily of low-fat cottage cheese, fat free cheese, or a dairy-based protein powder like whey protein.

The main point with all of these protein sources is to provide a source of high-quality protein while avoiding as much carbohydrate and fat as possible.

Most of these protein sources will inevitably have a small amount of carbohydrate and fat along with them, and that's OK to some extent. In general, up to 4 grams of combined fat and carbohydrate per serving is acceptable. Any more than that will start to slow your weight loss and diminish all the effort you're putting in, so be careful.

Vegetarian and Vegan

Between the protein drink and the allowed dairy items, this diet is vegetarian-friendly.

Unfortunately, this diet can't be done properly by vegans since most plant sources of protein contain more starch than this diet allows. Soy, pea, and rice protein in powder form are a possibility. However, with all of your protein coming from just a few powdered sources, there's a real danger that you wouldn't be getting the right amount and type of nutrients and amino acids to keep you safe and healthy on a very low-calorie diet like this. So we don't recommend that this diet be done by vegans.

How Much Protein?

The amount of protein you eat is customized to your specific situation. It depends on a combination of your BMI, your dieting group, and your activity level. The diet plan setup calculator will tell you exactly how much protein to eat.

Your protein intake depends partly on your activity level. There are three basic levels: None, Aerobic, and Resistance. For most people, these levels are referring to the type of exercise you will be doing outside of your normal, everyday activity. In other words, it's your dedicated exercise time. For a few people, an exceptionally physical job might qualify them for higher exercise levels. Read through the following descriptions to help you decide which level you fall under.

• Resistance/Aerobic. Resistance exercise is activity that involves the movement of heavy weights to strengthen muscles. It's generally weight lifting, but can also involve using your body weight as with push-ups and sit-ups. Choose this level if you are doing any kind of resistance exercise at least two or three times a week. If you are doing aerobic exercise in addition, you should still choose this level. In certain cases, your job might qualify you for this level. If your job requires you to do heavy lifting for at least 30 straight minutes a day, choose this level.
• Aerobic Only. Aerobic exercise is activity that involves sustained, repetitive movement that raises your heart rate and lung capacity. Good examples are jogging, swimming, and biking. Choose this level if you are doing only aerobic exercise (no resistance exercise) at least three times a week. In certain cases, your job might qualify you for this level. If you spend a lot of time on your feet -- say two straight hours or more every day -- especially if it gets your heart rate up, you might need to choose this level in order to help you maintain the right energy levels for your job.
• None. Choose this level if you are not exercising at all or if you're doing minimal or very light exercise, such as walking twice a week. This level is perfectly fine while on this program.

The diet setup calculator will tell you how many total grams of protein to eat every day. You need to divide that amount into your daily meals; the calculator will assist you with that, too.

Note that your daily protein intake refers to the grams of actual protein contained in the food, not the weight of the food itself. Some of the allowed foods contain more protein than others. Often the same type of food will contain different amounts of protein depending on the cut, manufacturer, or brand. For example, a cube steak might have a different amount of protein than a pot roast, and the same cube steak from different companies might have different amounts of protein, as well.

In order to determine how much protein you're getting from a given food, you'll need to do a little math. Here are three methods you can use for this.

Method 1: Calculate It

Here is an example. The nutrition facts label on the left is for chicken breast. Note that the serving size is 4 oz, and the amount of protein in each serving is 26 grams.

Let's say you are preparing a meal where you want to eat 40 grams of protein. What you need to find out is how many ounces of this chicken is equal to 40 grams of protein - so you can measure it on your food scale. Here's what you'd do:

1. Calculate how many grams of protein is in each ounce: 26g divided by 4oz = 6.5 grams per ounce
2. Calculate how many ounces you need to get 40 grams of protein: 40 grams divided by 6.5 = 6 ounces (rounded to nearest ounce)
3. Measure 6 ounces of chicken breast on your food scale.

Method 2: Estimate It

If you don't have the nutrition facts, you can estimate protein fairly simply by using the following guidelines:

• Three (3) ounces of meat is roughly the size of your palm (also about the size of a deck of cards).
• On average, cooked meat contains 8 grams of protein per ounce, and raw meat contains 6 grams of protein per ounce.
• That means a palm-sized portion of meat contains roughly 24 grams of protein cooked, or 18 grams raw.

So for example, two palm-sized portions of raw meat would be roughly 6 ounces (3oz x 2) and contain 36 grams of protein (18g x 2). This kind of estimation won't be completely accurate but it's often close enough.

For estimating the content of other protein sources, you can use the following numbers:

• Cottage cheese contains 14 grams of protein per ounce.
• Beef jerky contains 10 grams of protein per ounce.
• Cheese contains 8 grams of protein per ounce.
• Egg whites contain 3.5 grams of protein per egg.