When I wrote about why the ketogenic diet is total B.S., the internet didn't take it too well. People on Facebook called it "false," "intellectually disingenuous," and even straight-up "terrible." One reader even devoted a whole blog post to dissecting the information line-by-line.

The keto diet — a low-calorie, high-fat eating plan touted by celebrities and Instagrammers alike — aims to activate the metabolic process called ketosis, when our bodies use fat for energy instead of sugar. Followers say it's helped them lose weight and gain energy, and they still get to eat bacon and butter.

My response: The ketogenic diet may work for you personally right now, and if that's the case, then go for it — as long as you inform your physician about your diet, medical history, and medications. It's your choice to eat keto and make it work for you.

But from a public health standpoint, making a sweeping generalization in support of this diet would be negligent. It's my job as a registered dietitian (RD) to evaluate all the research in the context of scientific consensus, study strength, and long-term risk factors. Collectively, the existing information indicates that the keto diet can lead to nutrient deficiencies and prove difficult to adhere to long-term.

Still, I read through every response to my original article. I've included some of those comments below, ones that represent common opinions about the keto diet, to elaborate on where I stand:

1."There's a ton of research on ketogenic diets."

"This article is so intellectually disingenuous. The author obviously spent little time researching ketone production and its use through all of human evolution. Keep eating sugar and promoting the S.A.D. diet. It's killing people perfectly well." — Brett R.

You're right that there is some research on the ketogenic diet, but not much looks at the long-term effects on overall health and weight maintenance. The best studies conducted for more than one year looked at the impact of keto on pediatric seizure disorders. The benefits for epilepsy in these cases outweigh the potential risks.

In fact, one 10-year study conducted on keto and epilepsy management in children found the following side effects: constipation (65%), high triglycerides (40%), high cholesterol (29%), diarrhea (19%), lethargy (17%), iron deficiency (15%), and vomiting (13%).

As for the Standard American Diet (SAD), I am absolutely not suggesting that we don't have big challenges when it comes to healthier eating habits, but my less-than-enthused stance on keto isn't because I'm comparing it to SAD. Rather, I think it's important to compare a keto plan to its weight-loss counterparts, like the well-substantiated Mediterranean diets and its spin-offs, like DASH, MIND, and TLC. Those plans incorporate wholesome, nutrient-dense foods that encourage improved eating patterns and manageable weight loss.

2."It's not just butter and coconut oil."

"I do not subsist in butter and coconut oil. Nor am I bored eating bacon and cheese omelettes and prime rib. I make sure I take supplements so my systems function like clockwork. We have lost a total of 113 Lbs between the 3 of us which is a whole lot more than 'water weight.'" — Theresa G.

It's true that the diet is not just butter and coconut oil, but it's still quite high in saturated fat. A lack of boredom doesn't imply that it's a health-promoting plan either.

You said it yourself: You take a supplement to protect yourself from deficiencies, including (but not limited to) iron and zinc. You're also at risk for missing potassium, magnesium, folic acid, and beta carotene. Know that the FDA doesn't oversee supplements, so you may not be getting exactly what you pay for. Plus, certain nutrients consumed as supplements can also have a pro-oxidant effect, meaning they do more harm than good. The end result: Increased risk of chronic disease, including heart disease and some cancers.

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I'd also encourage you to have a look at photos tagged #keto on social media: beverages loaded with heavy cream, cheeseburgers without buns, and lots o' processed meat. So while it's possible to consume foods both compliant with the diet and nutritious, the messaging surrounding keto is the perceived ability to eat tons of fast food and skimp on sprouts.

3."It's outdated to say that 'low-fat' is good for weight loss."

"I don't eat keto however the research in this article is terrible. It supports the outdated notion that low fat is good for you...a little secret it's NOT. Since America's diet has shifted from high fat to low fat, diabetes and heart disease has become an epidemic. Fats are not killing us, sugar is. Keto is not going to harm your body, but continuing to eat processed foods is." — Jessica P.

I couldn't agree with you more that extremism in our diet culture has created undeniable issues as a result of low-fat, high-carb processed foods. But the point of the keto debate is not comparing it to junk food, but rather the benefits of a Mediterranean-style eating plan.

Yes, diets high in refined sugars and breads are linked to obesity, but turning from one extreme to another is not the solution to the obesity epidemic.

We know that extreme diets such as keto may induce weight loss. However, recent studies indicate that the extreme fat intake required to bring the body into ketosis may also have negative effects. A 2015 review published in Nutritional Neuroscience found that keto can increase risk of diabetes, heart attack, and strokes in children treated for epilepsy — risks considered less significant than enduring seizures, but ones not beneficial for the overall population, 49% of which is at risk for heart disease.

Another meta-analysis published in the British Journal of Medicine in 2013 evaluated ketogenic diets versus low-fat diets for long-term weight loss. It found that keto works for weight loss short-term and may lower blood pressure, but it can also increase LDL cholesterol.

The authors also say their own research analysis overlooked key indicators of health: Liver function, vascular function, cardiovascular events, and kidney function. In other words, we don't necessarily know the harm that ketogenic diets can cause.

4. "I've lost weight and kept it off."

"Works great for me. I lost all the weight I wanted to lose and have kept it off. I like eating this way and I've felt better than I ever have!" — Heather S.

Your eating habits are personal, and if you wan to lose weight, then you should follow the plans that work best for you! That said, it's still crucial that you look into whether or not you're meeting all of your nutrient needs in food form in order to remain healthy over time. The fact that there's not much research on the overall sustainability of ketogenic diets is what prevents many nutritionists from recommending it universally.

That said, if a particular eating plan causes immediate weight loss, and subsequent gain once you stop, that's not solving any medical or public health issues long-term.

Diet-induced weight fluctuations factor in heavily when healthcare professionals give advice, especially because RD's like me always look to apply the most current, well-researched scientific data to whomever we counsel. A big component of that is weighing benefits versus risks, and what we do know is that there may be some risky long-term effects of frequently gaining and losing weight. Extreme diets promote doing just that.

It may be more helpful to put into this context: If we were talking about a medication instead of food, would you consider it sound advice to say that taking a certain drug "might be safe, but definitely not safe for everyone, and it may only work temporarily and cause damage to other biological systems?" Not so much.

The point of the keto debate is not comparing it to junk food, but rather the benefits of a Mediterranean-style eating plan. Getty Images

5. "This diet reversed my type 2 diabetes."

"I have been on keto for almost a year. I was on the verge of being placed on insulin with diabetes 2. Since having started keto I have lost 50lbs. My HDL has gone up and my LDL has gone down as have my triglycerides. My blood pressure is the best that it has ever been. My A1C is at a 5.3 and I have gotten off my high blood pressure meds and cholesterol meds and my numbers continue to be great." — Sebastian T.

First of all, congratulations! Significant weight loss is a tremendous accomplishment, and I applaud you for getting where you are now.

To your point, this is where the benefits come in: Losing more than 10% of your body weight when you're overweight or obese can significantly improve your metabolic state of health, regardless of how you got there! With that in mind, it's likely your type II diabetes "reversed" course thanks to the weight you lost — not the diet itself.

However, if you are diabetic and considering a ketogenic diet, it's essential that you know this: "Ketogenic diets may help some people with type II diabetes lose weight and therefore reduce blood sugar, but they're not safe for everyone with diabetes," says Dr. Elise Brett, Associate Clinical Professor in the Division of Endocrinology, Diabetes and Bone Disease at the Icahn School of Medicine at Mount Sinai Hospital. "One should always check with a doctor before starting this type of diet."

Many diabetes medications actually require eating some carbohydrates to ensure they work. "Diabetes medications avoid low blood sugar reactions, and people who take insulin and/or [medications] called SGLT-2 inhibitors may put themselves at risk for a life-threatening condition called diabetic ketoacidosis (DKA) in which ketone levels in the blood reach dangerously high levels," Dr. Brett adds.

While some keto studies have shown improved blood glucose levels, nearly all of the research conducted to-date states that the strict parameters have a side effect of decreased adherence over time.

If keto's too restrictive to maintain for forever, it can lead to weight cycling, or gaining and losing a lot of weight when "dieting" versus when you're not. This can lead to impaired glucose tolerance, chronic inflammation, and possibly higher cardiovascular disease risk.

The bottom line: Don't cut back on nutritious foods for the purpose of weight loss.

The more interest grows in the topic (on either "side" of the debate!), the more research will occur. But let's zoom out before we zealously advocate for any diet limited in plant-based foods. Cutting back on these nutritious foods for the purpose of weight loss can propagate myths about balanced diets. It also creates continued confusion and a culture of extremism that's not suitable or sustainable for everyone.

To make real, long-term changes, we can't rely on restriction. We have to approach health and weight loss with an understanding of our own lifestyle, and shift toward healthier eating habits through behavior changes that last a lifetime.

Jaclyn London, MS, RD, CDN, Good Housekeeping Institute Director, Nutrition Lab A registered dietitian with a Bachelor of Arts degree from Northwestern University and a Master of Science degree in Clinical Nutrition from New York University, Jaclyn “Jackie” London handles all of Good Housekeeping’s nutrition-related content, testing, and evaluation.

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