If you want me to take the claim that "a high protein diet is unhealthy" seriously, then you're going to have to provide something better than that article.
"Weight Gain" due to increased protein consumption is disputed[1]. In fact the premise itself can be disputed just by noting that weight gain can present itself in the form of muscle gain.
Bad breath: ...really?
Constipation: "This is because high-protein diets that restrict carbohydrates are typically low in fiber." I'm sorry, but why do high protein diets need to be low in fiber? That doesn't make any sense at all - any diet can be low in fiber if you don't eat fiber.
Diarrhea: Author provides no source.
Dehydration and Kidney damage: Both prevented by drinking enough water.
Increased cancer risk: The issue with these studies is that they don't provide necessary controls. Most people who eat red meat regularly are not doing HIIT, strength training, or going for walks. They are not eating their red meat on a bed of spinach. They are eating it between two buns and with a side of steamy fries (which are known to cause cancer[2]). If we look at the actual mechanisms for carcinogenicity, we find that eating veggies, not burning your food, and not eating cured meats, are probably as likely to keep you cancer free than switching your steak to a super whole-grain diet. Don't forget to also have a healthy gut, which prevents colon cancer[3]
Saturated Fat / Heart Disease / cholesterol: Again, no long term studies have had the right controls in place to conclude that Saturated fat, in the absence of unhealthy carbs/meats, are actually harmful. Only 20% of the cholesterol in our bodies actually comes from our food. Saturated vs nonsaturated is a debate being waged between actual RDs. It's not just "an effort to cloud an issue".
Calcium Loss: Actually, more Americans experience calcium loss as a result of NOT getting enough protein.
"Despite a widely held belief that high-protein diets (especially diets high in animal protein) result in bone resorption and increased urinary calcium, higher protein diets are actually associated with greater bone mass and fewer fractures when calcium intake is adequate. Perhaps more concern should be focused on increasing the intake of alkalinizing fruits and vegetables rather than reducing protein sources." [4]
Whether high fat and protein vs high carb low fat is "better", is going to remain debated until the end of time, because studies repeatedly show discrepancies.
The fact is humans from different geographies have evolved over time to accommodate different diets. This is why we see things like lactose intolerance concentrated in some regions but devoid in others [5]. Imagine ALL of the other mechanisms for body health and how they have evolved over time in different regions, and consider how silly it is to attempt to expose those which are harmful using broad studies with poor controls over only certain populations - while ignoring the underlying mechanisms for the actual harm.
Saturated fat intake has been shown to boost serum cholesterol and increase risk of CVD in literally hundreds of direct feeding mechanistic trials. Genetic variability of cholesterol is high enough that cross-sectional studies are not appropriate for studying this.
In other words, ingesting saturated fat and cholesterol will raise your cholesterol levels and increase your risk of CVD but your baseline risk depends a lot on your genes.
The mayo clinic link is actually reaffirming my opinion:
>For most healthy people, a high-protein diet generally isn't harmful, particularly when followed for a short time. Such diets may help with weight loss by making you feel fuller. However, the risks of using a high-protein diet with carbohydrate restriction for the long term are still being studied.
They are still being studied - poorly at that.
The second link is hilarious in that it fails to even describe the two types of LDL cholesterol, but lumps them both in as "bad" - which is typical of the "cholesterol is bad" crowd. In fact - the first study I clicked on in the nutritionfacts.org fails to mention the same. How can you do a study on cholesterol without even testing the two types of LDL? Frankly, it's embarrassing and is absolutely not mechanistic as you say.
Once again, these meta studies are attempting to show that a diet with lowered saturated fat intake is better in the long run than your average diet. This is not something that anyone is debating. However, it absolutely can not be misinterpreted as proof that high protein/saturated fat intake, in all cases, is bad. Which is exactly the mistake all of these authors are making, and is why there are many intelligent people on the other side of this discussion as well.
>"Large" LDL is marginally less dangerous than "small" LDL
Neither large nor small cholesterol are "dangerous" - it's black-and-white opinions like this that make the nutrition industry so difficult for laymen to follow. They are both healthy, in that without cholesterol you would die. Excessive amounts of certain cholesterols in ratio to others just happen to be symptoms of underlying eating disorders. The author states that:
"She ... argues that HDL, so-called good cholesterol, also rises maintaining the ratio of bad to good. This is the study she cites to support that assertion. But instead of cherry-picking this one study that she performed with Egg Board money, involving 42 people, if you look at a meta-analysis, if you look at the balance of evidence, the rise in bad with increasing cholesterol intakes is much more than the rise in good."
However, it is known that the ratio of HDL to total cholesterol is a just as good as if not a better predictor of heart health. That's why it is generally used... [1]
There are many documented cases of high protein diets (or more specifically - low carb) achieving better cholesterol ratios [2][3][4]. There are also many more studies that address the significance of LDL size, than what the author you linked addresses [4][5][6]
[1] Mensink, Ronald p., et al. “Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials” The American Journal of Clinical Nutrition 77.5 (2003): 1146-1155.
[2] Bueno, Nassib Bezerra, et al. “Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials.” British Journal of Nutrition 110.07 (2013): 1178-1187.
[3] Brinkworth, Grant D., et al. “Long-term effects of a very-low-carbohydrate weight loss diet compared with an isocaloric low-fat diet after 12 mo.” The American journal of clinical nutrition 90.1 (2009): 23-32.
[4] Merchant, Anwar T., et al. “Carbohydrate intake and HDL in a multiethnic population.” The American journal of clinical nutrition 85.1 (2007): 225-230.
[4] Otvos, James D., et al. “Clinical implications of discordance between low-density lipoprotein cholesterol and particle number.” Journal of clinical lipidology 5.2 (2011): 105-113.
[5] Meisinger, Christa, et al. “Plasma oxidized low-density lipoprotein, a strong predictor for acute coronary heart disease events in apparently healthy, middle-aged men from the general population.” Circulation 112.5 (2005): 651-657.
[6] Parthasarathy, Sampath, et al. “Oxidized low-density lipoprotein.” Free Radicals and Antioxidant Protocols. Humana Press, 2010. 403-417.
https://www.healthline.com/health/too-much-protein#risks
You're also getting saturated fat and cholesterol with the steak, which is unhealthy despite recent efforts of some to cloud the issue.