For weight loss purposes, protein is the best macro-nutrient you can eat. Diets higher in protein (25% or more of total calories) -- especially lean protein sources -- are typically the most successful. See some studies below.

As well, research shows that a higher protein intake after losing weight reduces the chance of regaining weight during weight maintenance, and if any weight is re-gained it tends to be lean body mass instead of fat.

Why Does Protein Work So Well?

Protein is more filling than fats, carbs... even more filling than fiber. In studies, protein has been shown to be superior for both short-term and long-term satiety.

It also has the highest TEF (thermic effect of food), meaning it takes the more energy to digest and process than other nutrients -- your body uses up 20 - 30% of the energy in protein for processing which means you're actually only netting 70 - 80 calories for every 100 grams of protein you eat! Compare that to 100 calories of carbs and fats which only require 2 - 6 calories of energy to process.

Studies also show that higher protein intake limits the loss of lean body mass on low-calorie programs.

Finally, protein is the least likely of all the macronutrients to turn to fat, in virtually every metabolic or diet circumstance (see Losing and Gaining)

Instructions

Include protein with every meal and every snack, if possible. Especially lunch. And breakfast.

Lean or Fatty? Protein is still protein and can help you stay full and lose weight (but take it easy on the bacon!). However, if you are trying to cut calories as low as possible then you should choose Lean Protein (lean meats and low-CD dairy).

Suggested Protein Intake
RDA (Recommended Daily Allowance)	0.36 grams per pound (0.8 g/kg)
First 3 weeks of ketogenic diet*	0.8 grams per pound (1.75 g/kg) or 150 g, whichever is higher
Endurance athlete*	0.54 - 0.63 grams per pound (1.2 - 1.4 g/kg)
Weight training*	0.72 - 0.81 grams per pound (1.6 - 1.8 g/kg)
Weight training common estimate*	0.8 grams per pound (1.8 g/kg)

* Calculate using LBM (lean body mass) if available. Otherwise, total weight is fine.

Lean Proteins
Meat and Dairy protein shake (if low carb) beef and veal (extra-lean) chicken breast (skinless, boneless) turkey breast (skinless, boneless) beef jerky (check labels and avoid extra carbohydrates) buffalo or bison egg whites (no yolk) cottage cheese (low-fat) cheese (fat-free)	Fish (low-fat, typically white-fleshed fish) albacore tuna cod crab crayfish flounder grouper haddock halibut lobster orange roughey shrimp snapper sole striped bass tilapia turbot

Fatty Proteins
Meat and Dairy bacon pepperoni pork salami duck game meat ham hot dogs lamb liver sausage of any kind spam eggs whole milk Greek yogurt	Fish anchovies salmon sardines oysters catfish clams bass herring mussels trout tuna (except albacore	Nuts Macadamia Pecans Hazelnut Etc

Vegetarian/Vegan Protein Sources

If you are avoiding meat or dairy and don't mind some extra carbs along for the ride, here are some great protein sources:

Quinoa*
Beans, Lentils
Hummus
Soybeans, soy products*
Other seeds: chia, hemp, amaranth
Buckwheat*
Vegan protein powder

Vegetables/Plants:

Spinach
Artichokes
Peas

* = Complete protein source

Note you can get complete proteins in your daily diet through simple combinations like a grain plus beans (e.g., rice beans), or by eating a wide variety

Research and Studies

One study found that people who ate high-protein meat at lunch, rather than a high-carb lunch, ate 12% less at dinner.

Another study found that eating eggs for breakfast, rather than a bagel, felt more full and ate fewer calories over the next 36 hours.

Similarly, another study found that a people who ate a protein-rich breakfast of eggs and lean beef felt more full and made better food choices later on.

In one study, women ate a 160-calorie yogurt snack that was either low, moderate or high in protein (Greek yogurt). The study found that those who ate the high-protein Greek yogurt felt full the longest and were less hungry.

Studies have proven the real reason why low-carb dieting is successful for the average person (who isn't diabetic) isn't because carbs are reduced; it's because when carbs are restricted, people end up eating more protein!