You learned in our previous post about how a ketogenic diet causes your body to switch from glucose to ketones for fuel. Your body goes through a transition period while it’s making this change, so it’s natural to experience some shifts in the way you feel during that first week or so of your keto diet reset.

To help set some clear expectations around the transition, I outlined the general timeline for getting into ketosis and what you may experience along the way. Keep in mind, that there are exceptions to this timeline, as some people reach ketosis sooner than average, while others may find the process slower than expected. While everybody is different, the outline below gives you a general sense of what the experience is like to transition into ketosis.

Pro tip: If possible, I recommend starting the keto diet on a Thursday, as days 3 and 4 are usually the hardest part of the transition. With a Thursday start day, the toughest days fall on Saturday and Sunday which can give your body and brain a bit more grace throughout the transition (this advice applies to the M-F worker bees, of course, feel free to adjust your start day to best accommodate your schedule).

Day 1

Your first day on keto, you’ll probably feel fine. What causes the most struggle during that first day (the first few days, really) is figuring out your macro ratios and what it actually looks like to eat 75% fat. It’s a big change for most people compared to the Standard American Diet. Keeping your protein low (around 15%) can be tricky too, especially if you’re used to eating lean meats. You’ll quickly learn that your options are to 1 ) eat a very small amount of animal protein, or 2 ) pick fattier cuts.

Day 2

You might not feel your best today – typically, the second day is the beginning of what is known as the “carb flu.” The carb flu is the experience of flu-like symptoms that come from your body being starved of carbohydrates. Your body is hard at work figuring out how to keep going without glycogen. Some symptoms you may begin to experience are headaches, fatigue, muscle aches, nausea, brain fog, and irritability. If you find yourself suffering today, remember that this is normal and will soon pass!

Day 3

Buckle up. This will probably be the worst carb-flu day you experience. Your body is realizing it’s not getting carbs anymore, and the transition process to begin breaking down fats for fuel can feel brutal at first. Be really gentle to yourself during these days of your keto transition – there is no need to exercise if you’re feeling lethargic or nauseous. Try to keep activity to a minimum, and if you can, minimize how much work you have to do, too.

Day 4

You can see some light on the other side! Today should be a better day than yesterday. Your body is getting used to running off of fats for fuel, and the worst of the transition process is behind you. It’s normal to continue feeling slight fatigue and malaise, so don’t be discouraged. Use your newfound energy to meal prep for the upcoming week, as preparation is your key to success during your first few days. If you need some help, tag in our local chefs to cook some of your keto meals (order by Thursday at midnight to get your meals Monday morning). 

Day 5-7

Towards the end of the first week, you’re likely hitting your groove. By now, you have an understanding of what it looks and feels like to eat a diet that’s 70-75% fat and very low carbohydrate, and entering your food into My Fitness Pal should be much speedier than it was in the beginning. Look at you go, keto rockstar!

You may not have officially hit ketosis yet, but you’ll know if you’re close based on where your ketone levels read (thanks to your urine or blood tests). Some people can hit ketosis in their first week, but many do not. If you haven’t yet hit the mark, don’t worry. It’s perfectly normal to still be transitioning. Keep testing and keep the faith!

Day 8-10

So many good things start to happen at the start of this second week. The majority of people will hit ketosis by day 10, and you’ll likely be feeling pretty good by now.

• Your carb-flu symptoms have probably dissipated, and you’re used to eating a high fat diet.
• You might find your energy actually increasing at this point, and notice that “2pm slump” is a thing of the past. Carbs are the cause of the spike and drop of blood sugar throughout the day, so now that you’re limiting your carb intake, you shouldn’t feel that anymore. Most people report feeling a steady energy that lasts all day.
• You may feel like you aren’t that hungry, and have to remind yourself to eat.
• Remember to prioritize water intake as you hit ketosis. The high amount of ketones in the body can lead to dehydration.

Now that you’ve made it to the other side, enjoy all the benefits that a keto diet has to offer!

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