How to do keto right

This high-fat, low-carb way of eating has grown in popularity for its benefits to brain health, inflammation, weight loss, and blood-sugar stability. On keto, you typically eat no more than 50 grams of carbohydrates a day, with a makeup of roughly 70% fat, 20% protein, and 10% carbs.¹ It’s helped countless people — but a few essentials make all the difference. Let’s start with the difference between “dirty keto” and “clean keto.” (New to keto? Start with our introduction to the ketogenic diet.)

Dirty keto (what not to do)

Let’s start with what not to do. On “dirty keto” you’ll still eat high fat, moderate protein, and low carbs — and you may even reach ketosis — but your body won’t get the nutrition it needs for the long run. If you’re not spending any time preparing wholesome meals, you’re probably here. Dirty keto tends to:

Clean keto (what to focus on)

Done the right way, keto means investing a little time and energy in high-quality, whole foods you prepare yourself. Your body will thank you. Focus on:

Keto vs. paleo-keto: should I have dairy?

Traditional keto allows dairy; paleo-keto does not, with the exception of ghee for those who tolerate it. If you’re considering keto, you may wonder whether to drop dairy and go paleo-keto. A few questions to consider:

• Do I have a dairy sensitivity? If so, dairy can cause gas, bloating, abdominal pain, fatigue, headache, or brain fog — and ignored, a food sensitivity can drive chronic inflammation. IgG and IgA lab testing can reveal delayed reactions (up to 5 days later). We often find people with chronic illness are sensitive to dairy without realizing it. A sensitivity also triggers an adrenal response that can raise blood sugar and keep you out of ketosis.
• Do I have celiac or a gluten sensitivity? Dairy is cross-reactive with gluten — meaning your body can see dairy as gluten and mount the same inflammatory response. (More in gluten, dairy, and autoimmune thyroid disease.)
• Do I have an autoimmune condition? Because autoimmunity is driven by inflammation, it’s best to avoid dairy — along with gluten, one of the most inflammatory foods. (See what is autoimmunity.)
• Am I focused on weight loss? If weight loss is the priority, removing dairy can help lower inflammation and support your goal.

Glycemic index & net carbs

The glycemic index (GI) ranks a food’s carbohydrates by how much they raise blood glucose.⁵ Because not all carbs behave the same, the idea of net carbs was created. Net carbs are the carbs left after subtracting fiber — since the fiber in whole foods generally isn’t digested and absorbed, it doesn’t spike blood sugar.

On keto you typically keep total carbs under 50 grams a day — and it’s also helpful to keep net carbs between about 15 and 30 grams a day. For example, a small banana might have 18.5 g total carbs; subtract 2.1 g of fiber and you get 16.4 g net carbs — already at the low end of the daily limit from one banana. Not a great keto fruit.

Sugar alcohols

Most of us have a bit of a sweet tooth, and this is where sugar alcohols come in — though there’s some debate around them. Sugar alcohols taste sweet like sugar but have fewer calories and resist digestion somewhat, like fiber. (Despite the name, they contain no ethanol; the term reflects their chemical structure.) Like carbs, not all are the same — here’s roughly how some sweeteners compare on the glycemic index:

While xylitol, sorbitol, and maltitol won’t raise blood sugar as much as sugar, they still affect it. Erythritol, on the other hand, is fully absorbed in the small intestine and excreted unchanged in the urine, with no effect on blood glucose or insulin.⁷ So when a food’s carbs come from erythritol only, you can subtract them from total carbs, just like fiber. For example, a dark-chocolate bar sweetened with erythritol listing 22 g total carbs, 12 g fiber, and 6 g erythritol works out to 22 − 12 − 6 = 4 g net carbs. One caveat: sugar alcohols can cause bloating or an upset stomach in some people — if erythritol bothers you, it may be best to avoid it.

Am I in ketosis?

It can take 7–30 days to reach ketosis. Before you get there, you may feel the “keto flu” — your body adapting to a new way of making energy, switching from glucose to ketones. Keto flu is actually a sign you’re approaching ketosis.

• Keto flu. About 2–7 days in, you may get brain fog, headaches, fatigue, and nausea. We don’t know exactly why it happens, but drinking plenty of water, adding sea salt, and eating colorful vegetables all help.
• Fatigue. Short-term fatigue is common, largely from early water and electrolyte loss. Stay hydrated and increase electrolytes and salt.
• Digestive changes. You may swing between constipation and diarrhea early on. Eat lots of colorful veggies and stick with it.
• Insomnia. In the first few weeks you may sleep poorly or wake at night — but many keto dieters report better sleep as they continue.⁸
• Keto breath. A fruity breath from acetone (one of the ketones) is common early on and fades as your body adjusts.

• Higher blood ketones. The most reliable measure. Nutritional ketosis runs about 0.5–3.0 mmol/L, measured with a finger-prick home meter.
• Ketones in breath or urine. Less reliable but convenient — breath meters and urine strips both work.
• Weight loss. Often quick in the first week (mostly water and stored carbs), then steadier if you stick with it.
• Less hunger. People on keto often feel satisfied and less driven to snack.⁹
• Better focus and energy. After a few weeks, many report sharper cognition. Research finds keto can be neuroprotective, especially in traumatic brain injury¹⁰ and Alzheimer’s.¹¹

Fasting and keto

Intermittent fasting has become a popular way to lose weight and gain other benefits — studies find it can help control blood sugar and reduce inflammation, and it can trigger autophagy, the body’s process of clearing out damaged cells to regenerate new ones. The most common approach is the 16/8 rule: eat within an 8-hour window and fast for 16. There are good reasons to pair it with keto:

Final thoughts

When you take the plunge into keto, expect some changes — you’ll feel them for the first few days or even weeks (see keto flu above). Stick with it and your body will adapt, and you’ll start to feel the benefits. Above all, get enough plant foods and do “clean keto,” not “dirty keto” — a diet high in fat, especially saturated fat, without enough plants can leave you very inflamed. As always, work with a functional health practitioner to make the best choices for your particular body. We’d love to help you reach your goals.