Sales of grass-fed beef have exploded in recent years, as more and more people start to question how their food is produced.
Not only is it supposed to be better for you than regular beef, grass-fed beef contains higher levels of conjugated linoleic acid (CLA), a type of fat sold in pill form as a weight loss supplement.
It also has a lower ratio of omega-6 to omega-3 fatty acids, with some claiming that this makes grass-fed beef more “anti-inflammatory” than its grain-fed counterpart.
Unfortunately, buying grass-fed beef because you think it’s going to help you lose fat is largely a waste of money.
While it does provide around twice as much CLA as regular beef, grass-fed beef still contains only a tiny amount of CLA.
The table below (taken from this study) shows how much CLA you get per 100 grams of fat from both grain-fed (control) and grass-fed beef.
As you can see, for every 100 grams of fat from grass-fed beef, you get just 1 gram of CLA. That’s not a lot.
For CLA to have any kind of effect on body fat, you need a relatively large dose — somewhere in the region of 3-4 grams per day.
Unless you’re eating massive amounts of beef every single day you won’t get anywhere near this amount.
And even if you could, the research on CLA and weight loss is nothing to get excited about.
There are plenty of studies out there to show that CLA “does something” for body composition. But there are also many others to show that it has absolutely no effect whatsoever.
And even in the research that does show a faster rate of fat loss with CLA, the effect is a relatively minor one.
In one meta-analysis, which involves researchers combining the results from a number of different studies, CLA was found to cause “a modest, but significant, reduction in fat mass of about 0.09 kilograms (0.2 pounds) per week relative to subjects in placebo groups.”
So even if you’re taking 3-4 grams of CLA per day, the “something” that CLA does isn’t of any great consequence, and its effect on your body composition is likely to range from very small to completely non-existent.
Does the CLA in beef work better than the CLA in a supplement?
Most CLA supplements contain a 50:50 blend of two different isomers – cis-9, trans-11 (c9,t11) and trans-10, cis-12 (t10,c12). The c9,t11 isomer makes up 75% or more of the total CLA in beef.
In other words, c9,t11 is the “natural” isomer, while t10,c12 is the “artificial” one. And because it’s natural, the c9,t11 isomer is also considered by many to be the most effective.
A 16-week study published in the Journal of Nutrition compared the two to see which one worked best for fat loss. The researchers divided a group of 81 healthy women into three groups.
• The first group served as a control and took 5.5 grams of olive oil per day.
• Group two took a CLA supplement that was made up of c9,t11 and t10,c12 CLA. This is the artificial mixed CLA found in most supplements.
• Group three took only c9,t11 CLA, which is the natural isomer that makes up the majority of the CLA found in beef.
The group taking the artificial CLA mix lost just two pounds of fat during the 16-week study. Both the olive oil and c9,t11 CLA groups actually gained fat.
In other words, the natural form of CLA was less effective than the artificial one.
What’s more, food that’s been naturally enriched with extra CLA has not been shown to do much of anything.
Researchers from Iowa State University found that a diet naturally enriched with over a 3-fold increase in CLA from pasture-fed cattle had no effect on body composition, insulin sensitivity or other health markers compared with a similar diet composed of foods from grain-fed cattle.
Milk enriched with CLA also had no effect on blood lipids or body composition in moderately overweight men and women, while a 10-fold increase in the CLA content of butter fat had no beneficial metabolic effects in overweight or obese men.
There is much talk about the fact that grass-fed beef has a lower ratio of omega-6 to omega-3 fatty acids, which is supposed to make grass-fed beef more “anti-inflammatory” than conventional beef.
While it’s true that grass-fed beef is higher in omega-3 fatty acids than grain-fed beef, they still amount to less than one per cent of the fat found in beef.
For every 100 grams of fat from grass-fed beef, you only get about 1 gram of omega-3 fatty acids. Most of it is alpha-linolenic acid, which is the short-chain omega-3 fatty acid found in flaxseed.
A ratio means nothing if your total dietary intake of a particular type of fat is low. If you want to get more omega-3 fatty acids in your diet, you’ll be far better off eating more high-fat, cold-water fish (such as salmon) or taking a fish/krill oil supplement.
In short, unless you’re eating massive amounts of beef every day, the small differences in fatty acid content between grass-fed and grain-fed beef aren’t large enough to have much of an impact on anything worth measuring.
Grass-fed beef may, on the whole, have a superior nutritional profile to regular beef. But if you’re buying it because you think it’s going to change your body composition for the better, you’re wasting your money.
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About Christian FinnChristian Finn holds a master's degree in exercise science, is a certified personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Fit Pro, Zest, and Perfect Body magazine. You can contact Christian using Facebook, Twitter, Google+ or via e-mail.