What’s up with weight-loss supplements?
Ah, weight-loss supplements. I do love reviewing the evidence in this area. It is remarkable how people, or more aptly named salesmen, saleswomen, or salesperson as it is 2021 after all, can take the slightest shred of potential benefit and create the most outlandish claims around a single mystical supplement! In reality, people have been doing this for years in order to sell products and make a profit, i.e. snake oil salesmen. Unfortunately, some of these individuals in the past were from my profession! Adding alcohol and various other illicit substances to cure your ailments – I mean, if you are drunk or high, your ailment does become less of a concern…soo they did kind of work! Alas, morals and ethics became front of mind over the years, and getting your patients stoned or drunk is generally frowned upon.
Similarly, I feel I now have the moral obligation to dispel the stories and myths of the snake oil salespersons of today! Currently, there are various ‘weight-loss supplements’ out there, so this will obviously be a series of blogs. I have already reviewed the evidence around Apple Cider Vinegar here, but today we are talking about CLAs or Conjugated Linoleic Acids!
What are Conjugated Linoleic Acids or CLAs?
I had to do a bit of research to answer that very question. CLAs are actually a naturally occurring fatty acid found in meat and dairy products. Researchers consider it as a healthy fat. I know, isn’t fat supposed to be unhealthy? But CLAs are made up of polyunsaturated omega-6 fatty acids – so indeed, they are considered a healthier fat that we should strive to consume more of!
As a caveat in case you go and look up CLAs on your own – some might say that CLAs are trans fats – which we know are bad news bears. Hence why many government agencies have worked to ban the use of trans fat in food industries. However, there is a distinct difference – CLAs are naturally occurring trans fats which, compared to industrially produced trans fats, do not seem to have the same negative health effects. Still, more evidence is needed to tease this point out fully.
What can CLAs do?
Well, that really depends on who you ask. Craig, the IG influencer, will tell you that CLAs can prevent cancer, help with insulin resistance, blood sugar levels, lipid levels, blood pressure, weight-loss, and give you the life you have always dreamed of. However, if you ask me, the pessimist and realist, I will say, “Craig can go catch a chicken, and the claims around CLAs are way overblown.” The majority of the claimed health benefits have come from animal studies and small/poorly done human trials and have not shown any real significant benefit.
Well, how did my friend Susan lose weight while taking CLAs?!
First off, Susan was consistently in a calorie deficit. So there is that, but to give you a more detailed answer, I pulled a systematic review and meta-analysis from 2019 done by Namazi and friends. In these kinds of studies, the authors pull the data from multiple studies and combine it all together through magic and wishes in order to summarize and average all the data in a given area. The theory and mechanism as to why CLAs would work for fat loss sounds good – the authors stated that CLAs are thought to decrease the size of fat cells, regulate fat metabolism, and stimulate pathways that can lead to fat cell death. Woah, this is precisely what we want! Death to the fat cells!
Now it’s not like the results were negative. I would say they were more neutral than anything and maybe some benefit in weight and fat loss, but nothing worth writing home about. There was a lot of variability between the combined studies due to different methodology and reporting of results. As well, some of the studies included other interventions such as increased activity and a calorie deficit diet. So, are the results seen due to CLA or the other interventions? Finally, most of the studies were of low quality. Nonetheless, let’s look at some forest plots below.
Forest plots list all the combined studies and show the overall average of all of those studies at the bottom. Depending on which side of the vertical line the little diamond at the bottom falls on tells us whether CLAs were beneficial or not. In the case of the two plots below, the diamond is trending towards the left, indicating CLAs may have benefits in weight-loss and fat-mass loss.
In terms of weight-loss, the results were significant when compared to placebo. CLAs, on average, reduced body weight by ~0.52kg or ~1lb. Older adults >44 years old and participants receiving higher doses of CLAs >3.4g/day may have had more benefit losing on average ~1.05kg and ~0.77kg, respectively. When CLAs were taken for more than 12 weeks, more weight-loss was seen ~1.29kg! Similar trends were seen with changes in fat-mass loss. On average, ~0.61kg was lost. A longer duration led to a loss of ~1.94kg. Older adults again seemed to get more benefit, losing ~1.79kg. Mind blown. Right? Where have CLAs been all of our lives?! In case you are wondering, this was #sarcasm. In terms of safety, CLAs seem to be OK – main side effects reported for nausea, stomach upset, diarrhea, constipation, headaches, backaches, and eczema (not sure the mechanism for that one but something to consider).
Well, considering a 1-month supply of this stuff can cost you ~$20-$40 on Amazon, I do not believe the minute benefit is worth it. To be honest, I am a bit hesitant about the trans fat aspect and would like to see more data in that regard. However, if you are dead set on trying it – I would say older adults >44 years old are going to get the most benefit, and you will need to ensure you are taking a dose >3.4g/day. As with anything to do with weight-loss, buckle in for a long-haul use! Or, you could save those pennies and buy some high-quality protein instead!
That is all for today, my friends. Always remember: small tweaks lead to massive peaks!
– Dr. Dan
Namazi N, Irandoost P, Larijani B, Azadbakht L. The effects of supplementation with conjugated linoleic acid on anthropometric indices and body composition in overweight and obese subjects: A systematic review and meta-analysis. Crit Rev Food Sci Nutr. 2019;59(17):2720-2733. doi: 10.1080/10408398.2018.1466107. Epub 2019 Jan 22. PMID: 29672124.