It’s easy to get caught up on the “low-carb” part of the diet and not give enough attention to the “high-fat” part. Fat is what makes you full, gives you energy (when in ketosis), and makes food taste delicious. For most people this figure should be north of 70 percent of daily calories. Keep carbs under 20g, hit your protein goal, and eat fat until you’re full.

The ketogenic diet is a high-fat, adequate-protein, low-carbohydrate diet that in medicine is used primarily to treat difficult-to-control (refractory) epilepsy in children. The diet forces the body to burn fats rather than carbohydrates. Normally, the carbohydrates contained in food are converted into glucose, which is then transported around the body and is particularly important in fueling brain function. However, if there is little carbohydrate in the diet, the liver converts fat into fatty acids and ketone bodies. The ketone bodies pass into the brain and replace glucose as an energy source. An elevated level of ketone bodies in the blood, a state known as ketosis, leads to a reduction in the frequency of epileptic seizures.[1] Almost half of children and young people with epilepsy who have tried some form of this diet saw the number of seizures drop by at least half, and the effect persists even after discontinuing the diet.[2] There is some evidence that adults with epilepsy may benefit from the diet, and that a less strict regimen, such as a modified Atkins diet, is similarly effective.[1] The most common adverse effect is constipation, affecting about 30% of patients—this was due to fluid restriction, which was once a feature of the diet, but this led to increased risk of kidney stones and is no longer considered beneficial.[2][3]
The reason you eat a balanced diet, which includes fruits, vegetables, dairy, protein, grains, legumes, nuts, and seeds, is to get a variety of nutrients your body needs to stay healthy. You can do so on a lower calorie diet *and* successfully lose weight. However, on the keto diet, grains, legumes, and fruit are pretty much eliminated (berries, watermelon, and apples are allowed sparingly). These food groups provide a ton of nutrients including fiber, phytonutrients, and antioxidants like vitamins A and C. Keto dieters are also known to have constipation because of the lack of fiber in their diet. (FYI, here are the supplements you should take if you're on the keto diet.)
Another reason for the quick weight loss when you start a keto plan is water loss. “Nitrogen is one by-product of breaking down protein for fuel,” says Notte. “Free nitrogen floating around the body is toxic, so the body flushes it out with frequent urination.” This loss of fluids shows up as pounds lost on the scale. But it can also lead to dehydration and an imbalance of electrolytes—the minerals and salts your muscles rely upon. This is why some keto dieters get terrible leg cramps, Notte explains. “The same thing happens with the Atkins diet—keto is just today’s version.” Make sure you know what happens to your body on keto.
In many developing countries, the ketogenic diet is expensive because dairy fats and meat are more expensive than grain, fruit and vegetables. The modified Atkins diet has been proposed as a lower-cost alternative for those countries; the slightly more expensive food bill can be offset by a reduction in pharmaceutical costs if the diet is successful. The modified Atkins diet is less complex to explain and prepare and requires less support from a dietitian.[54]
The ketogenic diet is a mainstream dietary therapy that was developed to reproduce the success and remove the limitations of the non-mainstream use of fasting to treat epilepsy.[Note 2] Although popular in the 1920s and 30s, it was largely abandoned in favour of new anticonvulsant drugs.[1] Most individuals with epilepsy can successfully control their seizures with medication. However, 20–30% fail to achieve such control despite trying a number of different drugs.[9] For this group, and for children in particular, the diet has once again found a role in epilepsy management.[1][10]

How did this diet, which was first developed in the 1920s as a treatment for children with epilepsy (and has been shown to reduce seizures in patients whose epilepsy symptoms aren’t responding to other medications), become the diet du jour, and why such a discrepancy between its fandom and expert opinion? Let’s take a closer look at what “going keto” entails.
But people who started following the keto diet noticed weight loss for a few reasons: When you eat carbs, your body retains fluid in order to store carbs for energy (you know, in case it needs it). But when you’re not having much in the carb department, you lose this water weight, says Warren. Also, it's easy to go overboard on carbohydrates—but if you're loading up on fat, it may help curb cravings since it keeps you satisfied.
Other forms of ketogenic diets include cyclic ketogenic diets, also known as carb cycling, and targeted ketogenic diets, which allow for adjustments to carbohydrate intake around exercise. These modifications are typically implemented by athletes looking to use the ketogenic diet to enhance performance and endurance and not by individuals specifically focused on weight loss.
"It was extremely difficult," he recalls. "You spend your entire life hearing that fat makes you fat and causes heart attacks and strokes. Now, all of a sudden, you're eating 200 grams of fat per day. There is a huge psychological component to conquer before you can become successful with the keto diet. In the beginning, it's like trying to convince people 1,000 years ago that the world is in fact round, not flat."
Carol- so sorry to hear about your stroke. I am not sure most doctors would approve of this diet due to most not being taught much on nutrition in med school, and most still believe in the old school high carb low fat way of eating. My experience has been a dramatic drop in my blood pressure in only a few weeks after starting this diet (172/105 down to 144/95!). I suggest giving it a trial of a few months to see how it may work for you.
As far as keto's track record with longer term weight loss, a systematic review and meta-analysis that looked at 13 randomized trials that lasted at least a year showed that people who followed the ketogenic diet recommendations lost, on average, 2 more pounds compared to those who followed lowfat ones. But some experts say that weight loss from a keto diet probably isn't from any specifics about the diet itself. If the ketogenic diet aids weight loss, says Brian St. Pierre, R.D., director of performance nutrition at Precision Nutrition, it’s because it might enable some people to maintain a caloric deficit.
On the ketogenic diet, carbohydrates are restricted and so cannot provide for all the metabolic needs of the body. Instead, fatty acids are used as the major source of fuel. These are used through fatty-acid oxidation in the cell's mitochondria (the energy-producing parts of the cell). Humans can convert some amino acids into glucose by a process called gluconeogenesis, but cannot do this by using fatty acids.[56] Since amino acids are needed to make proteins, which are essential for growth and repair of body tissues, these cannot be used only to produce glucose. This could pose a problem for the brain, since it is normally fuelled solely by glucose, and most fatty acids do not cross the blood–brain barrier. However, the liver can use long-chain fatty acids to synthesise the three ketone bodies β-hydroxybutyrate, acetoacetate and acetone. These ketone bodies enter the brain and partially substitute for blood glucose as a source of energy.[55]
The most science-backed performance-boosting supplements, such as creatine monohydrate, beta-alanine, and caffeine, are all A-OK on the ketogenic diet. So, if you take a pre-workout, you should be able to continue without issue. I would also recommend gulping down some bouillon before your session to ensure your sodium and magnesium levels are on point.

But if no carbs are available, our bodies start burning fat as a primary fuel source and producing ketones in the liver, which the body can turn into energy. This metabolic state, called ketosis, is what happens when someone is starving. But it's also how Harper's body works every day. His system relies on fats like butter, oil, and lard as a primary energy source instead of packing them on as in-case-of-emergency poundage.

If you have been looking for a weight loss plan, however, you've probably heard of one of the ketogenic diet’s biggest claims to fame: the quick results it supposedly produces. Some people report losing as much as 10 pounds in the first two weeks. But this weight loss is likely to be mostly water weight, not fat melting away, meaning you stand to gain it back once you replenish fluids. The ketogenic diet can act as a diuretic, causing water loss from glycogen storage in the liver, muscles, and fat cells. Keep in mind that for most people, about ½ pound to 2 pounds per week is considered safe.
Protein will induce an insulin response in the body, if consumed in high amounts. The most intuitive way to start a keto diet for most people is by removing all of the carbs they have been eating. Typically people will replace those calories by increasing their lean meat consumption. That's a recipe for disaster! Keeping protein moderate is an often overlooked, but very important part of a keto diet. Most people need around 0.6g to 1.0g of protein per pound of lean body mass.
Also, when you eliminate sugar and high-carb foods from your daily diet, "your body is able to heal itself and detox from the accumulated inflammation that it is constantly fighting," That means less brain fog, improved cognition and brain health. Consequently, the improved mental clarity makes it easier for you to make smart food choices, adds the nutritionist.
This is a well-known phenomenon with nearly every type of diet: If you relax the rules even a little bit, you suddenly find yourself overeating. Making entire food groups—such as grains, sugar, and other carbohydrates—off-limits helps make them even more attractive, Macri says. This type of reaction goes beyond a psychological reaction—it can also be physical, she says. “Serotonin is one of the feel-good brain chemicals, and when serotonin decreases, such as it does when you’re on a strict low-carb diet, the brain is on high alert for any kind of reward,” she explains. Let some sugar or bread into your diet, and you could be overcome with a desire for more, Macri warns. “This makes it much more likely that you’ll overeat or even binge on those foods.” 
In its 2016 report “Healthy Eating Guidelines & Weight Loss Advice,” the Public Health Collaboration, a U.K. nonprofit, evaluated evidence on low-carbohydrate, high-fat diets. (The Keto diet falls under the LCHF umbrella.) Among 53 randomized clinical trials comparing LCHF diets to calorie-counting, low-fat diets, a majority of studies showed greater weight loss for the Keto-type diets, along with more beneficial health outcomes. The collaboration recommends weight-loss guidelines that include a low-carbohydrate, high-fat diet of real (rather than processed) foods as an acceptable, effective and safe approach.