Two decades ago, we used to laud carbs, demonise fat, and nobody except for serious athletes and bodybuilders really gave a second thought to protein. How times have changed. Protein is, of course, still the macronutrient of choice for anyone looking to put on or maintain lean muscle, but the remarkable benefits that protein can have on fat loss have been recently been embraced by a society that is struggling with its weight. So why is protein so great?
Firstly, we've learnt that 30% of the energy value of protein is required for its digestion, as opposed to 5-10% for carbs and next to nothing for fat. This is known as the 'Thermic effect' and it means that when we eat protein, our bodies are only getting about 70% of the calories consumed.
Secondly, protein builds muscle. Muscle not only looks good, but it is metabolically active tissue that burns a lot more energy than fat does. Because of this, the more muscle you have, the more energy you're going to burn throughout the day and when you're at rest. More muscle means a higher metabolism.
Finally, it is filling. As we've learnt more about the way carbs, especially sugars, influence metabolism and appetite, science has shown us that protein is a superior option for appetite control.
High consumption of protein is the cornerstone of most of the most popular diets this decade, including Atkins, Dukan and Paleo, and it definitely looks like the protein trend is here to stay.
Protein powders have moved from a niche market into the mainstream, and professional athletes are likely to be using a similar product to those people who are just trying to eat a little more healthily, even though it's quite obvious that those two groups have very different nutritional needs.
There has been a lot of research into the protein dosage and timing for muscle building and performance, but not such a great deal of work has gone into the use of protein for appetite control. On the other side of this, because of its ability to suppress appetite, a high protein intake potentially has the ability to displace other nutrients from an athlete's diet.
A group of scientists from Queensland decided to investigate this relationship in greater detail. The team assembled a small group of athletes, and had them consume either 20, 40, 60 or 80g of protein one hour after a standard breakfast. Three hours after protein supplementation, test subjects were provided with lunch at which they were allowed to eat as much as they wanted. The amount eaten by each athlete was recorded. Subjective feelings of hunger were recorded for each athlete throughout the experiment, and the subjects were rotated through all four protein treatment groups to give balanced results.
The results showed two very interesting trends. Firstly, as expected, all groups reported a decrease in hunger upon consumption of the protein shake. What was unexpected was the low variation in the amount that hunger was reduced. This only ranged between 50%-65%, despite a four-fold variation in protein dosage.
The second unexpected result mirrored the first. In spite of the large variation in protein dosage, researchers were very surprised not to find any significant differences in the amounts of food eaten between the four groups during the lunch.
This research allows two interesting conclusions to be drawn.
People who are using protein for weight loss are likely to see a similar extent of appetite reduction regardless of the amount of protein they use, within a given range. The fact that less is more is good news for dieters, not just for their caloric intake, but also for their hip pocket.
On the flipside of that is the idea that a large dose of protein is unlikely to get in the way of an athlete's consumption of other macronutrients. The researchers hypothesised that large doses of protein might be inhibiting an athlete's intake of carbs and fats, which in spite of the current reputation of the former, are both vital for energy and overall health. The findings of this experiment show that larger doses of protein are unlikely to affect overall macronutrient intake, but they do show that protein consumption has a big effect on appetite. This research suggests that an athlete may benefit more from fewer, larger doses of protein, while a dieter will have better results with multiple, small doses.
Of course, these conclusions would be better fleshed out with a larger experiment that also examined differences between athletes and non-athletes. While it does not take into complete account the myriad factors controlling appetite and food preference, this experiment certainly provides us with some interesting *cough* food for thought.
MacKenzie-Shalders K, Byrne N, Slater G, King N. The effect of a whey protein supplement dose on satiety and food intake in resistance training athletes. Appetite. 2015 May 12.