Latest / Common Sense Health / Low-Carb vs Low-Fat: Which One Actually Works?
Transcript
- Stephen Thomas BSc. Hons: Hello? If you feel like nutrition science is just two tribes shouting at each other, one saying fat's good, another saying carbs are good, just shouting it across the internet. You're not wrong, are you? But every so often someone does the unglamorous thing. They stop arguing. They collect the randomized trials and they count what actually happens. Now that's what the public health collaboration has done. They've compiled randomized controlled trials comparing low carbohydrate diets, which is defined as under 130 grams of carbohydrate per day, against low fat diets, typically defined as under 35 % of total energy from fat. And the headline is is not really subtle. mean, across this compilation, 62 out of 71 trials show greater weight loss on low carb than low fat. 39 of the 71 show a statistically significant advantage for low carb and zero. Yes, zero show a statistically significant advantage for low fat. No at all. So two are essentially a draw, by the way, which in nutrition science is the closest thing we probably have to a ceasefire. Now, before anyone warms up the it's all calories speech, yes, how much you eat does matter, but when you repeatedly see one approach outperforming another in real humans in controlled trials across different settings, the sensible question becomes, what is that approach doing that makes it easier to get the result? Now one point that's worth being honest about here is low carb under 130 grams is a range. It can mean a bit less bread or it can mean properly low carb as in under 50 grams and that matters if you want to answer a really practical question which is do the biggest wins happen when carbs go a lot lower than 130 grams? Now to explore that it helps to look at an example that's very clearly and unapologetically low carb. One study looked at an online intervention in people with type 2 diabetes comparing a very low carbohydrate ketogenic approach against a more traditional plate method style diet. Now the ketogenic intervention targeted 20 to 50 grams per day of non-fiber carbohydrate. So that's not sort of low carb. That's we've left the roundabout and we're on that low carb highway. By 32 weeks, the ketogenic group had a larger improvement in HbA1c around a 0.8 % drop compared to 0.3 % in the comparison group. They also lost substantially more weight, about 12.7 kilograms versus about three kilograms. Triglycerides improved far more. as well around a 60 milligrams per deciliter drop versus about six. And here's a detail that tends to get ignored because it's a little bit inconvenient. The dropout rate was dramatically lower in the ketogenic group, 8 % versus 46 % in the comparison group. So the group doing the strict diet were the ones who stuck with it. Now, that doesn't mean that keto is magical. It means that for many people, especially those with type 2 diabetes, or what I like to call carbohydrate intolerance, lowering carbohydrate exposure can make appetite regulation, glucose control and adherence noticeably easier. Now there's also related research comparing different macronutrient patterns like higher protein approaches in people with metabolic syndrome, showing meaningful changes in weight and body composition and metabolic markers over time. It's not the same question as low carb versus low fat, but it supports the bigger idea that changing the macronutrient mix can change the outcome. And not just by wheel power alone, by the way. So... We've got lots of evidence for that as well. Now, quick but important caveat, because this is where people get themselves in a muddle, really. When you're looking at blood results, interpreting the bloods in the context of a carnivore or ketogenic way of eating is absolutely crucial. Some markers can shift because the physiology shifts, fuel selection changes, insulin dynamics change, and what looks odd through a high carb lens can be perfectly coherent and understandable when you understand the context. So what's the takeaway from the public health collaboration ⁓ compilation? It's not that low fat never works. It's that when you line up the randomized trials, low carb is overwhelmingly more likely to produce greater weight loss. And in a large chunk of the trials, advantage, that advantage is statistically significant while low fat in this compilation doesn't show a statistically significant advantage even once. So if you run seven 71 trials on one side didn't get a single statistically significant win, most fields would call that a pattern. Nutrition, of course, is calling it controversial and then suggests you try some whole grains, some mindfulness and eat more fruit and honey. But if you care about results, especially with type 2 diabetes and metabolic health, this body of evidence is hard to just brush off. And when you look at the studies that go very low carb, the size of the effect often stops being interesting and starts being clinically relevant. And if that's the sort of joined up common sense approach you're looking for on the Internet, then you might want to subscribe to my channel or even join a community of like minded people in my common sense group online. The link is in the description is also on all of my sub stack articles, and it would be really nice to see you there as well. Anyway, if you've liked this ⁓ little short video, then please consider liking and subscribing. subscribing and commenting and even sharing it. That would be really great. If you've got to the end of this and you've just tut tutted all the way through, there are links to all the resources and references on my sub stack article. So just click on the sub stack and then you'll also get into the written article about this with a lot more nuance and you can actually read the studies for yourself. Anyway, thank you for listening. I'll see you on the next one.