The goal is weight loss

High-protein diets take their lead from the low-carb craze. The goal is to lose weight by eating more protein-packed foods, which often means consuming fewer carbohydrates. The portion of total calories derived from protein is what defines a high-protein diet. In a typical diet 10%-15% of daily calories come from protein. In a high-protein diet, this number can be as high as 30%-50%.

How do high-protein diets work?

Besides curbing appetites, it’s possible that high-protein diets may also change a person's metabolism. When carbohydrates are severely restricted, the body begins burning its own fat for fuel -- a state called ketosis. Ketosis may shed weight, but it's also associated with headaches, irritability, nausea, kidney trouble and heart palpitations.

Starting a high-protein diet

High-protein diets come in many forms, and not all are created equal. The most nutritious high-protein plans are low in fat and moderate in carbohydrates, rather than high in fat and low in carbohydrates. The following slides present a variety of foods that fit the high-protein diet bill.

Say hello to high-protein steak

Few foods beat a nice, juicy steak for protein. And if you're careful to choose a lean cut, you can get all of the protein with far less fat.

Think white meat

Chicken and poultry pack plenty of punch in a high-protein diet, and if you enjoy the white meat you’ll be eating a lot less fat than if you choose dark. To slim your meal down even further, remove the skin, which is bursting with saturated fat.

Look for pork loin

It may surprise you to learn that pork loin is a white meat. What's more, the cuts available today are much leaner than they were 20 years ago. If you're interested in a high-protein diet, you may want to plan on pork.

Lots of protein, healthy fats

Fish is a no-brainer - it's loaded with protein and almost always low in fat. Even the types that have more fat, such as salmon, are a good choice. That's because the fat in fish is generally the heart-healthy kind known as omega-3 fatty acid - and many people  don't get enough of this good-for-you fat.

Affordable, convenient and tasty

Eggs are perhaps the most classic and certainly least expensive form of protein. The British Heart Foundation has relaxed its stance on egg consumption saying there’s no longer a need for a healthy person to limit the number they eat. So you may want to get cracking with eggs when you're on a high-protein diet. If you’re concerned about the fat and cholesterol, egg whites are a good substitute and a heart-healthy source of protein.

Soya: It's high in protein, too

Soya products, such as tofu, soya burgers and other soy-based foods, are nutritious plant-based sources of protein. An added bonus: some research suggests consuming 25 grams of soy protein daily may also help maintain healthy cholesterol levels and protect against heart disease.

Beans and pulses : Full of fibre and protein

Beans pack a powerful double whammy -- they are loaded with protein and also full of fibre. Studies show that, along with protein, fibre helps you feel full longer and also helps maintain healthy cholesterol levels. As for the protein content, tinned baked beans have a sixth of the protein of grilled steak, but with a tenth of the fat.

Low-fat milk products

If you want to give your high-protein diet a tasty boost, don’t overlook dairy products as a protein source. Milk, cheese and yoghurt are not only protein-rich, they also provide calcium for strong bones and a healthy heart. Look for low-fat, light or reduced fat dairy products as part of a reduced calorie diet plan.

Cereal and energy bars

Pressed for time? You can turn to high-protein cereal or energy bars to give your high-protein diet a quick boost. Just make sure the bars you choose don't have too much sugar or fat.

Go wholegrain, go fibre

Most high-protein diets limit grains to a couple of servings a day, so make sure the grains you do eat are pulling their weight. That means staying clear of white bread and pasta, which have little to offer nutrient-wise, when compared with their wholegrain cousins. Wholegrain breads, cereals and pastas, on the other hand, are rich in fibre, which might otherwise be in short supply for people on a high-protein diet.

Leave room for fruit and veg

No matter the emphasis on protein, make sure you leave room for fruit and vegetables in a high-protein diet. As well as having at least 5-a-day, the NHS says they should make up a third of your daily diet. These nutrient gold mines also contain powerful antioxidants that aren't found in most other foods, and some research suggests that people who eat plenty of fruits and veggies may lower their risk of cancer, although more research is needed.

A diet that's easy to love

High-protein diets may help people lose weight - at least in the short term - because dieters tend to feel full longer when they eat more protein. This alone can cut down on snacking and lead to fairly rapid weight loss. Combine speedy weight loss with the satisfaction of feeling full, and it's easy to understand why high-protein diets are popular. Unfortunately, many people gain back the weight once the diet ends.

More protein, more risks?

The medical community has raised many concerns about high-protein diets. These diets often boost protein intake at the expense of fruit and vegetables, so dieters miss out on healthy nutrients – which could possibly increase their risk of cancer. Other potential health risks when high protein diets are used long term include high cholesterol, heart disease, osteoporosis and kidney disease.

More saturated fat, less fibre

Many high-protein diets are high in saturated fat and low in fibre. Research shows this combination can increase cholesterol levels and increase the risk of heart disease and stroke. These diets generally recommend dieters receive 30% to 50% of their total calories from protein. The British Nutrition Foundation recommends a balanced diet in which a smaller percentage of calories are derived from protein.

Losing calcium

People on high-protein diets excrete more calcium through their urine than do those not on a high-protein diet. If a person sticks to a high-protein diet long term, the loss of calcium could increase their risk of developing osteoporosis.

Protein may affect kidney function

People with kidney disease should consult a doctor before starting a high-protein diet. Research suggests people with impaired kidneys may lose kidney function more rapidly if they eat excessive amounts of protein - especially animal protein.

High-protein diets: Jury is still out

There are no long-term studies of high-protein diets, so their ultimate health impact is unknown. But the experts are sure of one thing: The best formula for permanent weight loss is a healthy lifestyle. This includes eating nutritious, low-calorie foods and participating in regular physical activity. Seek medical advice before making major dietary changes.

Related reading

• High-protein, low-carbohydrate diets
• The low-down on low carb diets
• The Mediterranean diet
• The truth about belly fat
• The South Beach diet
• The Dukan Diet plan