Ketogenic diets are all the rage right now, unless you’re reading this in 2027, in which case, ketogenic diets were all the rage in 2017.

My clients and even friends are starting to ask me about “going keto,” because they’ve heard it will help them lose weight, improve athletic ability, boost brain power, and achieve overall unicorn health status. A quick search turns up multiple headlines claiming a ketogenic diet can reverse epilepsy, cancer, diabetes, insulin resistance, and obesity and bring one to optimal health. So, is it all that? Is a ketogenic diet right for you, or is it just another fad?

What is a Ketogenic Diet?

A ketogenic diet mimics starvation, allowing the body to go into a metabolic state called ketosis. Normally, human bodies are sugar-driven machines: ingested carbohydrates are broken down into glucose, which is mainly transported and used as energy or stored as glycogen in liver and muscle tissue. When deprived of dietary carbohydrates (usually below 50g/day), the liver becomes the sole provider of glucose to feed your hungry organs – especially the brain, a particularly greedy entity accounting for ~20% of total energy expenditure. (a great synopsis from Scientific American).

Going keto basically means your body switches from burning glucose to fat for fuel. When you follow a ketogenic diet for a while, you enter into nutritional ketosis, which means your liver converts fats to ketones for fuel rather than than body burning glucose directly. A ketogenic diet excludes grains, starch, sugar, and fructose. It’s high fat, moderate protein, and very low in carbohydrates (quick lesson: anything that isn’t a protein or fat is a carb. That means wheat, grains, and legumes are carbs, but so are vegetables and fruits). Evidence is building that nutritional ketosis may be ideal for most people and could be the answer to a long list of health problems (source). But before we go all panacea, let’s look at some facts and determine if keto is all it’s cracked up to be.

I read somewhere that a ketogenic diet should be considered pharmaceutical in nature to treat a condition. This is a powerful statement and a testimonial to how profoundly one can use food to heal. This also means, like any fad diet, it’s not right for everyone, just as not every supplement or drug is right for every body. There are some individuals for whom this diet may cause more harm than good. I often preach that there’s no one right diet for everyone, and the keto diet is no exception.

Ketosis

First off, some basic info. Getting yourself into ketosis isn’t easy. You’ll need to cut down to 50 grams or less of carbs per day, or about 5 percent of your total calories. Some say 20 grams is ideal to get into ketosis initially. Just as a reference point, they average carb intake is around 300 grams per day, give or take, and 1 cup of sweet potato has about 30 grams of carbs. So yeah, you’re gonna kiss the starchy root veggies goodbye.

15- 30 percent of your calories should come from protein. This is about 50-100 grams or roughly 1 large chicken breast per meal (based on a 2,000 calorie diet). 60-75 percent (or even more) of your calories come from healthy fats. That’s roughly 5 avocados or about 11 tablespoons of coconut oil. But that’s the good news, because fat is tasty and keeps you full. So your individual breakdown will depend on how many calories you consume per day. For a 2,000 calorie diet, you’re looking at about 25 grams or about 100 calories of carbs; 92 grams or about 366 calories of protein; and 171 grams or about 1534 grams of fat. You can use this nifty calculator to see what’s right for you.

So the whole goal here is to get your body into ketosis so it’s burning ketones via fat as the primary fuel source. This is great if you’re overweight and want to lose fat, because you’ll be burning it right up. Remember, the liver produces ketones from fats when there’s no glucose, and ketones are a more efficient fuel source than carbs (source). Plus, your brain loves ketones. So you’ll hear a lot about getting and staying into ketosis and getting keto-adapted.

There are several tips for getting into and staying in ketosis, but you basically have to follow the very low carb, moderate protein and higher fat plan for at least 7 days, give or take, to even get there. You can get into ketosis quickly by fasting and burning up all your carbs. Some people combine intermittent fasting with ketogenic diets for this reason. It can take up to 2 weeks to get into ketosis, and during this time you can feel super crappy (called the “low carb flu”) as your body is making the switch from glucose to fat. Symptoms include headache, fatigue, constipation, brain fog, dizziness, muscle cramps.

How Do You Stay in Ketosis?

Once you’ve reached ketosis, you need to stay there to become a fat burning machine. That means you’ll have ketones to use continuously for fuel. Many researchers say ketones are “cleaner burning energy” than carbs that allow your metabolism to function more effectively. Make sure you’re eating plenty of healthy fats (see below) and don’t eat above your protein requirements. You can also get a meter to check your ketones and make sure you stay where you want to be.

What Do I Eat?

You’ll build your meals around low carb veggies (around 2 cups per day), fats and healthy oils, and moderate protein (a palm size or less).

• Good fats are the priority. Choose from coconut oil, MCT oil, olive oil, butter, ghee, avocado, avocado oil, and various dairy sources like cream, unprocessed cheese.
• Meat and fatty fish. I’m guessing you know what meat is, but choose from poultry, red meats, pork, salmon, tuna, sardines, trout, organ meats.
• Eggs
• Nuts & seeds: almonds, brazil nuts, walnuts, pumpkin seeds, cashews, and chia seeds are your best bets.
• Low carb veggies which are all the crunchy and leafy and none of the starchy. Think greens, cucumber, peppers, onion, cruciferous, tomatoes, etc.

You’ll avoid the following:

• Sugar of all types
• Grains and starches
• Fruit (though you can probably get away with small amounts of low sugar fruits like strawberries and blueberries once you become keto-adapted).
• Root vegetables such as potatoes, sweet potatoes, carrots, parsnips
• Vegetable oils or processed fats such as canola, corn, soy.
• Booze
• Beans & legumes

Benefits of a Ketogenic Diet

I most often recommend keto diets to those with over 30 pounds of weight to lose (especially if you have weight loss resistance); those with consistently high blood glucose levels or pre-diabetes; or those with cancer or epilepsy.

It is true that a ketogenic diet has profound effects on brain health and metabolic health. You can read studies and the laundry list of conditions a keto diet benefits here. Here are some additional benefits:

• Fast weight loss and improvement in cholesterol, lipids, and glucose levels (study)
• Blood sugar balance and enhanced insulin sensitivity
• Cancer treatment and prevention
• Increased satiety, decreased food cravings (not having to eat every few hours)
• Improved energy levels
• Ketones are awesome for brain health, and a ketogenic diet has neuroprotective benefits. Can be useful to treat epilepsy, seizure disorders, ADHD, Alzheimer ’s disease, memory, cognitive function, Parkinson’s Disease, and Multiple Sclerosis. You can see some of the studies here.
• Autism
• Mood stabilization in bipolar disorder
• Cardiovascular: Stroke prevention, metabolic syndrome management, improved cholesterol levels
• Inflammation management
• Endurance enhancement

My Concerns with a Ketogenic Diet

Are you sold yet? Not so fast. I’ve researched ketogenic diets pretty thoroughly, and there are downsides, many of which I’ve heard via my own clients’ health histories.

I use caution in recommending keto diets to women because they can damage a woman’s metabolism. This seems to happen more commonly (maybe only?) with women than men. I don’t have a source for this; it’s only what I’ve noticed from women with whom I’ve worked. But there is plenty of info out there about how low carb or keto diets down-regulate thyroid function (source), though that is still an oft argued point.

Women have delicate endocrine systems that are designed for reproduction and seem to suffer much more longterm with such intense carb restriction. The thyroid especially takes a hit, and that’s bad because it’s the metabolic powerhouse for the body, responsible for weight maintenance, fertility, body temp, cardiovascular function, and basically everything else. Restricting carbs affects thyroid hormone conversion and can cause longterm metabolic damage. If you’re hypothyroid or have a TSH above 2.0, keto is not for you.

Similarly, if you have low cortisol levels and struggle with chronic stress and hormone imbalance, avoid a ketogenic diet.

Secondly, a high fat diet doesn’t work well for everyone. Some people have trouble digesting and metabolizing fats, and high fat diets may cause inflammation in these people. Blame your genetics. We all have different metabolic needs, and that means some bodies run better with more proteins or carbs and and less fat. If that’s the case, a high fat diet may not work well for you. Further, the diet includes a lot of dairy (there are ways around this), which can cause digestive distress and inflammation in certain people, and I don’t recommend regular use of cheese or dairy. May cause loose stool or high triglycerides.

It’s super important to monitor your bloodwork while you’re doing keto to make sure your cholesterol and trigs aren’t taking a massive spike, which would indicate inflammation and a clue that this diet isn’t for you. Make sure your trigs stay under 100 and your trig: HDL ratio is 2:1 or less.

Thirdly, this diet takes serious dedication. It takes a lot of prep and research and may trigger some obsessive habits around food. If you have a history of disordered eating, take pause. You may also suffer some social limitations.

Also, it sucks to avoid fruit, legumes, and root vegetables. These foods have many digestive and overall disease-fighting benefits. The veggie rec for optimal health is about 6-9 cups of produce per day. On a keto diet you’re really restricted here, and that means you’re minimizing important disease-fighting antioxidants, fiber, and phytonutrients. Carbs are fuel for your gut bugs, and we don’t yet know the long term implications of a lower fiber diet on the microbiome.

Finally, some medical professionals think a ketogenic diet causes more longterm stress on the body. And because it’s kind of a fad thing right now we don’t know the longterm benefits or detriments to staying in ketosis. Is it really a good thing to mimic starvation? It may cause extra stress for the liver to make ketones.

As I mentioned, it can cause metabolic damage and hormone imbalance, and also menstrual irregularities, fertility problems, hypoglycemia, kidney stones, constipation (because of fruit & veg restriction), and nutrient deficiencies. (source) I’ve heard from more than a few colleagues and clients how bad they felt when in ketosis.

Bottom Line: in my opinion, men seem to benefit more from a ketogenic diet for quick weight loss and enhanced endurance. Obese women or women with more than 30 pounds to lose who do NOT have thyroid or endocrine imbalance may also benefit from a keto diet for weight loss, but ladies, approach keto with caution. A woman’s endocrine system may take more abuse from this very low carb diet.

I do think it shows amazing promise for cancer treatment, high blood sugar/insulin, and brain health. We also don’t have much info about duration and benefits (e.g. how long you should or need to stay in ketosis).

Have you gone keto? Please let me know your thoughts and how it’s worked for you in the comments.

Pin it!

Mary Vance (Certified Nutrition Consultant)

Mary Vance is a Certified Nutrition Consultant and author specializing in digestive health. She combines a science-based approach with natural therapies to rebalance the body. In addition to her 1:1 coaching, she offers courses to help you heal your gut and improve your health. Mary lives in San Francisco and Lake Tahoe in Northern California. Read more about her coaching practice here and her background here.