If you’ve been looking to lose weight, you’ve probably heard of the ketogenic, or "keto" diet. Supporters swear by the plan’s ability to promote weight loss without calorie restriction, while skeptics cite the strategy’s restrictive nature.
Want our two cents? Sure thing. Here, we provide a brief background on the keto diet, how it changes your body’s wiring, and whether we think you should give it a shot.
What is keto?
The ketogenic diet is a low-carb, high-fat (LCHF) eating plan.
Typically, a “low-carb” diet doesn’t have a prescribed allotment of carbs, but keto does: no more than 5% of calories from carbohydrates per day – essentially a medium apple or serving size of quinoa – to maintain the physiological state of ketosis, which we’ll get into shortly. This is a drastic departure from the average diet; someone eating 2,000 calories a day gets roughly 50% of those from carbs (about 250g) on average.1
So how does someone on keto make up those lost carbs? Fat. And a lot of it. In fact, keto dictates about 70-80% of total calories should be fatty ones, and only 15-25% should be from protein.
Although keto has been readily adopted as a weight-loss diet, it was created for a very different population: people with brain damage or brain-related disabilities. A ketogenic diet has been shown to reduce seizure incidence in pediatric epilepsy and even slow the progression of cognitive decline in those at an increased risk for Alzheimer’s.2,3
What happens to a body in ketosis
Your body can use multiple different molecules for energy (think anything that has calories), the easiest of which is glucose; machinery called mitochondria (yes, the “powerhouse of the cell,” your middle school biology teacher told you about) is set up to break these molecules down quickly and efficiently.
When you consume carbs, your blood sugar rises, kicking a hormone called insulin into action. Insulin pulls glucose from your bloodstream into your cells to use for energy. Keto’s aim is, in part, to keep insulin, and this process, dormant. After all, if glucose isn’t around, insulin won't be either. Thus, there's nothing left to stash away as fat.
During a glucose shortage, insulin’s opposite, a hormone called glucagon, switches your energy-producing machinery into ‘fat-burning mode.’ Eventually, when glucagon is left on interrupted (for about three days or so), fat breakdown in the liver creates small molecules called ketones, which most of the cells in your body can use for energy. This switch is known as ketosis.
What the research shows
Multiple studies have found that low-carb diets can help with appetite regulation and weight loss.1 And that’s not a coincidence; it certainly makes sense that a diet plan built on fat-burning forges a body that’s good at burning fat. But, given that keto as a weight loss tool is relatively new, there’s limited research regarding its ability to promote long-term weight loss and overall health; at present, the longest follow-up with keto followers is about two years.4
Why it’s like the ghosts of diets past
Just like other low-carb diets, the keto diet results in initial success as the body uses glycogen, a storage form a glucose primarily found in the muscles. Glycogen is stored with a fair amount of water, so as the body uses glycogen, it’s associated water is released. The result, a fair amount of water weight is lost.
So yes, being in a fat-burning state, burns fat, and if you’re trying to lose weight, that might seem like enough to hop on board. But like many diets, wavering from keto’s strict outline can negate its weight-loss benefits.
Unfortunately, even if you’ve sustained ketosis for a while, a carby slip-up can send you back to square one. Remember, on keto, your body’s glucose-processing machinery has essentially been turned off. When you finally do eat carbs, it can be slow to readjust. So while it powers up, your cells stash glucose away to replenish all of your body’s emptied stores.5 Prefer a summary? If you do eat carbs after being in ketosis, they won’t get burned for energy – they’ll stick around for a while instead.
Additionally, keto preaches that there's no need for calorie counting; if you aren’t able to dutifully track your carbs and also happen to go over, it can be a deadly combo for your weight loss goals.
The bottom line
Eliminating an entire category of food from your diet can result in faulty patchwork, especially if you don’t know exactly what your body needs. Often, keto followers replace lost calories from would-be healthy carbs like beans and whole grains with nutritionally inferior foods like processed oils, low-quality proteins, or highly-refined low-carb snacks. Similarly, whole, high-carb foods might be your main sources of micronutrients like folate, magnesium, and potassium; eliminating them all together might put you in danger of missing your daily needs.
When it comes down to it, our eating patterns are more than just what we put in our mouths. They’re also about the time we have to prepare food, the opportunities meals present to sit down with people we love, and, if we’re being honest, what we like to eat. So be honest about whether such a restrictive diet makes sense for your lifestyle.
If you’re looking to lose weight, start by getting your blood tested and identifying any gaps in nutrition. Address what’s already missing before removing giant swaths of foods – it might save you a difficult bounce-back period in the future.
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Some other blog posts we think you'll love:
-  Eric C Westman, Richard D Feinman, John C Mavropoulos, Mary C Vernon, Jeff S Volek, James A Wortman, William S Yancy, Stephen D Phinney; Low-carbohydrate nutrition and metabolism, The American Journal of Clinical Nutrition, Volume 86, Issue 2, 1 August 2007, Pages 276–284, https://doi.org/10.1093/ajcn/86.2.276
-  Henderson, C. Beth, et al. "Efficacy of the ketogenic diet as a treatment option for epilepsy: meta-analysis." Journal of child neurology 21.3 (2006): 193-198.
-  Krikorian, Robert, et al. "Dietary ketosis enhances memory in mild cognitive impairment." Neurobiology of aging 33.2 (2012): 425-e19.
-  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 110.7 (2013): 1178-1187.
-  Berg JM, Tymoczko JL, Stryer L. Biochemistry. 5th edition. New York: W H Freeman; 2002. Section 30.3, Food Intake and Starvation Induce Metabolic Changes.