My friend recently mentioned that he had lost a bunch of weight eating less protein but that seemed counterintuitive to what I've seen in my clinic and also amongst other friends. In general, healthy grains, unsaturated fats, vegetables and fruits are a great way to achieve a balanced diet... but what if you need to lose a lot of weight? Is protein our weight loss friend or foe?
When we talk about weight loss, there are a couple factors that affect weight loss success. Some of the main factors include satiety (feeling full), thermogenesis (our ability to burn calories), energy efficiency (how efficient our body manages our functioning and nutrients), and body composition (how much of us are muscle vs fat etc). It appears that dietary protein positively impacts these aspects and that's why I see weight loss in my patients who intake an appropriate amount of protein and less carbs.
Protein intake results in higher ratings of satiety compared to same caloric intake of fats or carbohydrates. This is likely due to oxidation of amino acids and ironically this affect is higher with ingestion of plant-based proteins compared to animal proteins. (1)
On the flip side, diet-induced thermogenesis is higher with animal protein intake rather than vegetable proteins. After ingesting protein, thermogenesis increases by 20-30% compared to 5-10% with carbohydrates and 0-5% after ingestion of fats. The increase in energy expenditure is from several biochemical processes including but are not limited by gluconeogenesis. (1)
What's even better is that when you are limiting your calories in order to lose weight, a relative increase in protein intake with help to maintain muscle mass and increase calcium balance which helps to preserve bone health. If someone has had a history of bariatric surgery, this is even more important because after surgery, protein absorption isn't as efficient and so a diet rich in protein would help prevent protein malnutrition. (1)
One common condition that frequently occurs in those who are overweight are glucose intolerance, pre-diabetes or diabetes mellitus type 2. There are suggestions in research that shows that intake of dietary protein can delay post-prandial blood glucose increase in those with sugar issues by stimulating pancreatic glucagon secretion. For those with poor sugar control, the positive impact of dietary protein intake for preservation of muscle and bone mass may be an added bonus since that may be issues in people with glucose intolerance issues. (1)
Having said all this, I need to throw out a few words of precaution. If you are trying to lose weight, please check with your doctor first before starting and make sure that the diet you are about to start on is safe for your specific personal health history. Secondly, those with hypertension, diabetes, kidney disease and the elderly population should be wary about adding more protein to your diet because too much protein for those who fall into these categories can prove to be problematic and dangerous. (1)
So, while I am a fan of having adequate protein intake for those trying to lose weight, there is not one cookie-cutter version for everyone (flashback to my friend as an example). So, please talk to your doctor and/or registered dietitian about what is a safe amount of protein for you to have in your diet to help with your weight goals... and at the end of the day, please remember that your body cannot run on one type of nutrient group alone so please keep vegetables, fruits, healthy fats, and unprocessed whole grains in your daily dietary intake regimen...these are needed to keep you healthy as well. Just remember, it's not just about weight loss...you want to reach a healthy weight goal but the key word is healthy and so that means more types of food groups than just protein. (1)
Happy eating to everyone and I hope you reach your goal weight!
References:
1. Keller, Ulrich. International Journal for Vitamin and Nutrition Research (2015), 81, pp. 125-133.