Points You’ll Take Away –
- Protein is not just needed to build and repair muscles, but also needed for the production of hormones, enzymes, antibodies and can also be broken down into amino acids during digestion and provide a source of energy.
- If we go with a thermic effect of 30% for protein, this means that 100 calories of protein only end up as 70 useable calories.
- Protein can reduce hunger and appetite via several different mechanisms (5) which can subsequently lead to a reduction in food intake.
- Unless calories are dropping very low protein will remain constant throughout your dieting/gaining phase and should stay in the range of 1-1.5g/lb of lean body weight. (16)
Protein is the single most important nutrient muscle growth, and weight loss.
A high protein intake helps improve health, reduce appetite and changes several weight-regulating hormones (1,2)
Protein is not just need to build and repair muscles, but also needed to build and repair all cells within the body.
They are also needed for the production of hormones which are chemicals produced by glands. Protein hormones bind to receptors on the cell membrane and cause a range of downstream effects on the body and coordinate activities. For example hormones control blood sugar levels, the control of puberty, egg and sperm production, pregnancy, birth. Control our fight or flight responses, control the feeling of hunger and even control our metabolism.
Proteins are also used for the production of enzymes. Molecules that bind to molecules to speed up chemical reactions. They are responsible for constructing, synthesising, carrying, dispensing, delivering, and eliminating the many ingredients and chemicals our body uses everyday. For example amylase and lipase are enzymes that help you to digest carbohydrates and fat respectively.
Antibodies of the immune system are also constructed of proteins. They are produced by the body to fight infection against bacteria and viruses.
Protein can also be broken down into amino acids during digestion and provide a source of energy. Although protein can be used as an energy source, the body’s main energy source is carbohydrates.
So what else does protein offer?
Digesting and Metabolising Protein Burns Calories
After you eat, energy is needed for the purpose of digesting and metabolising your food. This is known as the ‘thermic effect of food,’ TEF.
This biggest determinant of how many calories are used in digestion is the size of the meal followed by the protein content. (3)
‘Reported DIT values for separate nutrients are 0 to 3% for fat, 5 to 10% for carbohydrate, 20 to 30% for protein.’ (4)
If we go with a thermic effect of 30% for protein, this means that 100 calories of protein only end up as 70 usable calories.
Protein Reduces Appetite and Can Make You Eat Fewer Calories
Protein can reduce hunger and appetite via several different mechanisms (5) which can subsequently lead to a reduction in food intake.
The secretion of gut neuropeptides, small protein molecules used by neurones to communicate with each other, GLP-1, CCK, and peptide YY (PYY) seem to be increased in response to a high-protein diet to concentrations which lower hunger and increase satiety. (6,7)
GLP-1 blunted postprandial (after a meal) glucose response and reduced insulin release by reducing gastric emptying. This increased gastric emptying time, a test that measures the time it takes for food to empty from the stomach and inter the small intestine, lowered hunger and the desire to eat. (8)
CCK is a peptide hormone found in the brain and the gastrointestinal tract which significantly contributes to the inhibition of gastric emptying. Ingestion of dietary protein and especially digestion effectively stimulates CCK release in the gut. (9) It is now clear that CCK reduces food intake and meal size and induces satiety. (10)
An interesting study showed that when people increase from 15% to 30% of calories coming from protein, they automatically dropped their calorie intake by 441 calories per day. (11)
Protein Helps Prevent Muscle Loss
Weight loss doesn’t always equal fat loss.
What you really want to lose is body fat.
Losing muscle is a side effect of weight loss that is unavoidable, but the amount you lose is what matters.
Another side effect of losing weight is that the metabolic rate tends to decrease.
While reducing calorie intake and increasing energy output will aid in weight loss, doing this to extreme levels and drastically cutting calories will only result in problems.
Your metabolism adapts to the amount of energy you provide your body with. Its goal is to balance energy intake with output–to maintain homeostasis.
When you restrict your calories, your metabolism naturally begins slowing down and the more you restrict your calories, the faster and greater the down-regulation occurs.
Eating plenty of protein can reduce muscle loss, which in turn will help keep your metabolic rate higher as you lose body fat.
The degree to which muscle increases your metabolism is argued, but there is research showing lean body mass can increase your metabolism from 5-15% (12-15)
For this reason, a diet with sufficient protein is important, especially when dieting.
How Much Protein Should I eat?
Unless calories are dropping very low protein will remain constant throughout your dieting/gaining phase and should stay in the range of 1-1.5g/lb of lean body weight. (16)
In conclusion A higher protein intake is also associated with a lower body fat percentage. (17,18)
So look to consume a wide variety of foods with the majority your calories coming from from whole nutrient dense foods, getting sufficient protein fro ma variety of sources;
Eggs, Milk, Yogurt, Fish and seafood, Pork, Chicken, Turkey, Beef, Whey protein
But every now and then you can choose to enjoy some processed sugars in moderation.
You can eat your favourite surgery foods in moderation and you won’t suffer any adverse effects, and that’s absolutely true.
Eating a donut for example can coincide with your fat loss goals if you eat them within a calorie deficit. They are delicious, provide a different variety of taste from other carb sources and provide a balance in our lives.
Rather than a diet that is based around ‘good’ and ‘bad’ food, with no control over calories or macronutrients. Eat a wide variety of foods, you enjoy. Eat as many calories you can and the foods you love while still being able to reach your goal.
Plenty of fruit and veg, and yes that can be bought frozen, plenty of protein, and sufficient fat and carbs to fill up your total required daily calories.
So protein isn’t the sole reason you lose weight, but it can help you lose weight, it can also help you keep it off in the long-term. (19)
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