Dietary protein is your weight loss best friend. Not only does eating protein stimulate your metabolic rate so you release more energy as heat, but protein also has a powerful satiety effect, triggering the release of intestinal hormones that make you feel full for longer. These two effects make a higher protein, lower carbohydrate diet more effective for weight loss than a low fat or a low calorie diet. That’s why protein shakes and supplements are so popular that some health shops have wall-to-wall racks of powder in mega-tubs with added miracle ingredients for either weight loss, weight gain or enhanced performance.
The energy burning effect of protein
Proteins consist of long chains of amino acids linked together. Of more than five hundred amino acids found in nature, only twenty one are important for human health. These are broken down during digestion to release their individual amino acids for absorption.
Each amino acid is then processed individually within the liver, and – guess what – each has to activate its own individual metabolic pathway. So, proteins carry a high metabolic advantage and burn more energy during their processing than when you eat carbohydrates or fats.
In fact, an astonishing 25% to 30% of the energy derived from eating protein is lost as heat during its metabolism! That compares with 6% to 8% of the energy derived from eating carbohydrates, and 2% to 3% of the energy derived from eating fats, which is why higher protein diets are increasingly recommended to help combat overweight and obesity.
If you ate a snack providing 200kcals, of which half the energy was in the form of protein and half as carbohydrate, for example, you would derive around 183 usable kcals of energy.
If you increased the protein content of the snack so that 80% came from protein and only 20% from carbohydrate, you would ‘only’ derive 175 kcals usable energy – an extra 8 kcals energy is lost as heat during protein metabolism.
This may not seem like much, but if you added that up over the day then following a higher protein, lower carbohydrate diet could help you lose significantly more weight – or at least not gain weight – than if you ate the same amount of calories as a carbohydrate rich diet. And that’s before you factor in the effects of insulin, which is triggered by eating carbohydrate, and promotes fat storing and reduces fat burning (through effects on an enzyme called hormone-sensitive lipase).
The satiating effect of protein
Protein digestion stimulates the release of intestinal hormones which send signals to the brain indicating that you are full. This satiating effect of protein means you feel fuller for longer after eating a high protein meal, so you are less likely to have a snack attack.
Eat a boiled egg for breakfast, for example, and you will not experience hunger pangs mid-morning as you might after having a slice of toast. In one study, researchers from the University of Missouri gave a group of obese or overweight young women three different breakfast options, two of which supplied 350 kcal energy and one nothing at all. Those eating a protein-rich breakfast (including lean beef and eggs), had greater feelings of fullness throughout the day, reduced hunger and food cravings and less unhealthy evening snacking than those eating a bowl of cereal, or no breakfast.
Protein preserves muscle during weight loss
When on a diet, you want to lose fat while preserving muscle – apart from anything else, this helps to maintain your fitness, strength and body tone. Muscle also burns more energy than fat, so maintaining muscle helps to boost your metabolic rate. A high protein diet helps you achieve this.
At least 14 good quality clinical trials, involving 626 adults, have confirmed that taking a whey protein supplement improves weight loss when combined with resistance exercise. Overall weight loss averaged -4.20 kg total weight, -3.7 kg fat loss and increase in lean muscle (2.24kg) over 12 weeks in those taking whey protein supplements compared with controls. The conclusion was that the use of whey protein supplements, combined with resistance exercise as part of a weight loss or weight maintenance diet will improve body composition.
It doesn’t matter how old you are, either. One study tested this in 80 obese adults over the age of 60, who followed a 13 week weight loss program. All ate around 600 kcals per day less than their estimated energy needs, and followed a resistance training exercise program three times a week. In addition, half the volunteers took a protein supplement (a high whey protein blend enriched with leucine and provided 150 kcals for 21 g protein). The other half took a similar looking supplement which provided the same amount of calories, but no protein).
Both groups lost weight, with those taking protein supplements lowing 3.4kg compared with 2.8kg in those in the non-protein supplement group. Those taking protein also lose more fat mass (-3.2 kg versus -2.5 kg) and maintained more muscle mass.
High protein diets for weight loss
Eating more protein could help you shift those last few stubborn pounds. Popular diets such as the Atkins or South Beach diet are successful because they help to control your appetite and calorie intake while also stimulating your metabolism.
Most people consume around 15% of the daily calories in the form of protein. As a rough rule, an average adult needs around 1g protein for each 1 kg of body weight per day. Athletes are usually advised to have fifty percent more – 1.5g protein for every 1kg body weight per day – to maximise the growth and bulking up of muscle protein (in combination with exercise). This increased amount could suit those on a weight loss diet, too, so you obtain 30% of your energy in the form of protein.
A diet that supplies up to 30% of your energy as protein (twice the usual amount) is considered reasonable and could help you lose weight more effectively.
Researchers from the University of Minnesota analysed the diets of 1,824 women aged between 40 and 60 years and concluded that successful weight loss involved a combination of eating more protein and self-monitoring with a weight loss diary to achieve weight management.
Ideal protein weight loss program
A 4 week study compared the effects of following a very low energy diet (40% fewer calories than estimated needs) for 4 weeks in a group of 40 men who obtained these calories either from a higher protein diet (2.4 grams protein per kilogram body weight) or a lower protein diet (1.2 grams protein per kilogram body weight). All followed an exercise program (resistance exercise and high-intensity interval training) six days a week.
Lean body mass (muscle) significantly increased in the high protein group (1.2 kg) compared with the low protein group (0.1 kg). The high protein group also lose more fat mass than those on the lower protein diet (-4.8kg versus -3.5kg). These changes occurred even though the men were all consuming the same level of calories – just their source varied.
The conclusion was that, during a very low energy diet, consuming 2.4 g protein per kilogram body weight was more effective for weight loss than a diet providing 1.2 g protein per kilogram body weight.
The most important times to eat protein are first thing in the morning – to kick-start your metabolism. Aim to eat some protein with each meal to help keep you feeling full.
If you want to build muscle, then having protein after a work-out is when your muscles are primed to respond to the bulking-up effect of protein.
Should you take protein supplements?
While diet should always come first, using whey based protein supplement shakes are an ideal meal replacement strategy for weight loss.
A total of 21 amino acids are important for human health. You can make 12 of these within your cells from other building blocks when needed. The remaining 9 amino acids cannot be made in the body in sufficient amounts and must therefore come from your food – these are known as the nutritionally essential amino acids.
|Essential Amino Acids||Amino Acids you can make|
Protein supplements that include three particular branched chain amino acids (leucine, isoleucine and valine) are particularly important for muscle growth and repair.
Animal versus plant protein
Animal protein, such as meat, fish, eggs and dairy products (including whey protein) contain significant quantities of all the essential amino acids, including those known as the branched chain amino acids (leucine, isoleucine and valine) which are important for muscle growth and repair.
Most plant sources of protein (eg rice, beans, nuts, seeds) each contain some, but not all, of the essential amino acids. While soy protein does provide all the essential amino acids, it is relatively low in methionine.
If you follow a plant-based diet, eat a variety of foods, including beans, soy products such as tofu, nuts and seeds, plus rice and quinoa to ensure a balanced intake of essential amino acids.
Whey protein for weight loss
Whey proteins make up around 20% of the protein found in whole cows’ milk, and are obtained from the liquid whey that’s left after casein protein is solidified out to make cheese.
The whey is filtered and concentrated to remove water, then spray dried to make whey protein powder which will also include some milk fat and lactose sugar.
Whey isolate is made by removing all of this lactose and most of the milk fat.
Whey hydrolysate is made by partially pre-digesting the whey proteins to produce short chains of amino acids called peptides.
Whey protein is a great source of readily absorbable amino acids and is particularly rich in the branched-chain amino acids, leucine, isoleucine and valine, which help to preserve and build lean muscle. These help to maintain muscle mass while losing weight.
Whey protein is a great choice for weight loss. As well as helpling you feel full, and stimulating baft burning, whey proteins also have beneficial effects on glucose control, insulin responses, blood pressure, arterial stiffness and blood fat levels. Whey protein is therefore the best choice as a meal replacement or supplement for those who are overweight and have metabolic syndrome or type 2 diabetes. Whey protein also helps to lower blood pressure, if you have hypertension.
In people with type 2 diabetes, having 28g whey protein with breakfast can improve glucose control, and boost weight loss (7.6kg lost over 12 weeks) compared to those who did not add whey to their meal (compared with 6.1kg for adding another protein source, and only 3.5 kg loss with a high carbohydrate breakfast).
If you choose to avoid dairy products, or prefer a plant-based diet, then protein supplements based on pea, soy, nut or rice proteins are available.
Can you overdo protein?
For most people there are no concerns about increasing your protein intake to around 30% of daily energy intake. If you have diabetes, kidney or liver problems, however, check with your doctor first. If you have kidney damage as a result of diabetes, for example, you may be advised to limit your intake of protein.