Do Keto. Not Forever.

Short-Term Ketogenic Dieting for Metabolic Flexibility

Keto Diet

Keto Phases: More Benefits, Fewer Drawbacks

In 2018, at the peak of the keto frenzy, I was a ketogenic diet specialist who started spreading a very unpopular message from inside the keto community: Do keto. Not forever.

At that time, carbs were not welcome at the dining table. Many promoted keto as the "ideal" human diet, a lifestyle, and something you do forever. While I didn't want to discredit the value of doing (a temporary phase of the) ketogenic diet, I also wanted to be very clear: being in a state of nutritional ketosis for the rest of your life isn't optimal.

Why? Our bodies are designed to run primarily on carbohydrates. When we eat both fat and carbs, our bodies don't make ketones out of fat first. We only make ketones when our bodies are extremely deprived of carbs and have no other choice.

But given a choice? Our bodies will run on carbs. So why would the human body be designed to primarily run on carbs if we weren't "meant" to eat them? This should be your first clue: we are designed to eat carbs. In addition, our bodies will only use ketones for fuel when those carbohydrates are severely restricted.

Does that mean energy from ketones isn't as good? No. It just means the human metabolism is intelligently designed to do both. This natural adaptability also hints that it's something we should be able to do without suffering.

So let's get into the misconceptions about nutritional ketosis, carbs, and metabolic flexibility.

Getting what's described as the "keto flu" is a form of suffering. Dieters coined that term for the symptoms they'd experience the first time they went into nutritional ketosis. However, most people say these symptoms decrease (or disappear) each time they return to ketosis after taking a break.

This is a sign their bodies are becoming better at doing something they should easily be able to do – but have lost the ability to do well – because of the modern sedentary lifestyle and the food abundance that prevents it from happening often.

The truth is, nutritional ketosis is a healthy part of human metabolism. And an optimal metabolism should be able to function well in either of these states: glycolysis (running primarily on carbs) or ketosis (running primarily on fat that's been converted into ketones).

Fact 1: If you really struggle when you eat carbs, that's a sign of poor metabolic health.

Fact 2: If you really struggle being in nutritional ketosis, that's also a sign of poor metabolic health.

Being able to easily operate in either system is now commonly referred to as "metabolic flexibility." And that's the ticket. It's the ticket to improved energy, easier weight maintenance, and more food freedom, meaning you can eat according to actual hunger cues and be less likely to have weight issues.

I'm reminded of a line from the children's movie, Megamind:

"Girls, girls, you're both pretty."

Carbs are awesome. Keto is awesome. Everyone wins. And if you can thrive in either state, you'll win too.


Many people get lean without going into ketosis. So why bother? Lots of reasons. Here's a list of benefits from my book, Short-Term Keto:

  • Keto can improve cognitive function. Studies show that people with mild to moderate neurocognitive impairment experience improved executive function (working memory, flexible thinking, self-control) and speed of processing when on a ketogenic diet.(1)
  • Keto can reduce inflammation. Your mitochondria generate energy in the form of adenosine triphosphate (ATP) to fuel your cells. That process creates free radicals, also known as reactive oxygen species, as a byproduct.

Free radicals are unstable atoms that can damage cells, causing illness as we age. Obviously, since we produce ATP every second of our lives, our bodies are prepared for this. They minimize the damage by creating endogenous (meaning "made within the body") antioxidants like glutathione. But if the free radical load becomes too great, it causes us to age prematurely and increases our risk of stroke and neurodegeneration. Ketones can inhibit inflammation and oxidative stress by enhancing the breakdown of free radicals and increasing the activity of our innate antioxidant system.(2)

  • Keto can decrease appetite, making fat loss easier. A study that compared a ketogenic diet and a low-fat diet found that the participants in the ketogenic group experienced less hunger than those in the low-fat group.(3)
  • Keto can lower triglycerides. Studies on overweight and obese subjects found that a keto diet can drastically lower triglycerides, which are one of the biggest contributors to cardiovascular problems.(4)
  • Keto can increase good cholesterol. One of the easiest ways to increase HDL, your "good cholesterol," is to eat healthy fats. Keto definitely helps with this effort.(5)
  • Keto can lower blood sugar and insulin levels. Dropping carbs has led to impressive results for people with type 2 diabetes and insulin resistance. In one study of patients with type 2 diabetes and obesity, 95 percent eliminated their glucose-lowering medication within six months of starting a low-carb diet.(6)
  • Keto can preserve existing neurons and stimulate the production of new, healthy ones.(6)
  • Keto can help the body kill off old, damaged cells and create new, healthy ones.(7)
  • Keto can help heal and protect you from neurodegenerative diseases. For people with neurological disorders such as epilepsy, Parkinson's disease, Alzheimer's, dementia, or migraines, keto may be a life-changing healing modality.(8)
  • Keto can promote healing from autoimmune disease, polycystic ovarian syndrome (PCOS), some types of cancer, and metabolic syndrome.

While research is limited, a large amount of anecdotal evidence points to the promise of keto's impact on reducing inflammation and consequently autoimmune symptoms.

In research, implementing a ketogenic diet has been shown to reduce symptoms of PCOS, the most common endocrine disorder for women of childbearing age.

Rodent studies and small human studies have also shown the benefits of the ketogenic diet regarding cancer, particularly glioblastoma (an aggressive type of brain cancer), prostate, breast, liver, and stomach cancers. Scientists believe these benefits are due not only to the starving of the tumors, which feed on sugar, but also to the fact that keto changes gene expression, which in turn changes the way cells behave.

Nutritional ketosis serves as a treatment for metabolic syndrome by improving metabolic and inflammatory markers, including HbA1c, CRP, fasting insulin, and glucose levels, as well as aiding in weight loss, decreasing hunger, and increasing satiety.(9)

This is difficult to answer. Those who are already metabolically healthy, but haven't quite trained their body to thrive on ketones, might only need to do it for 4 weeks. Others who are very metabolically unhealthy might need to do keto for several years to get the full benefit.

I also must add that some people – a tiny percentage of the population – truly will do better on keto indefinitely. This includes people who are using keto as a therapeutic intervention for diseases such as epilepsy or other neurological diseases, type-2 diabetes, or autoimmune diseases.

For everyone else, here are some signs that keto has served its purpose and you're ready to reintroduce carbs to your body:

  • You just aren't feeling that great anymore on keto.
  • You're not getting the results you want, no matter what you do.
  • You're losing muscle and/or gaining fat on keto.
  • You've developed an unhealthy relationship with food, finding yourself in a
    restrict-and-binge cycle, for example.
  • You're not sleeping well.
  • You've had a gradual increase in anxiety since starting keto.
  • You have a general sense of unhappiness on keto.
  • Your exercise performance still sucks, and you've given keto at least several
  • You're overeating because you don't feel satisfied at the ends of your meals.
  • You have healthy blood sugar regulation and have no real reason not to eat
  • You're not eating carbs purely because, deep down, you're afraid you'll get fat if
    you do.
  • You have chronic watery stools or constipation on keto, no matter what you do.
  • When you do eat carbs, you eat all the unhealthy ones because "it's now or

Note: Please don't judge your keto experience by the first few days. This period can suck for most people. Your body isn't getting what it's used to (lots of carbs) and is adapting to operating in a completely new metabolic state. It gets better as it goes. And to make it better, get plenty of salt and water during your entire keto phase.


Slowly decrease your fat intake one week at a time. Replace those calories you'd be getting from fat with calories from carbs, which will increase each week (more details below).

The reason for the slow shift is multi-faceted:

Reason 1

To allow your body time to produce the correct amount of digestive enzymes so you can assimilate the changing macronutrients. You have different enzymes in your gut responsible for digesting proteins, fats, and carbs. Your body produces more or fewer of each type of enzyme in accordance to how you're eating. Doing this process gradually will help you avoid gut issues that often accompany drastic macronutrient changes.

Reason 2

To allow your gut bacteria to gradually adapt to the increased amount of fiber you'll be eating with increased carbohydrate consumption (because yes, your carbs should come from nature and have fiber content, not from candy).

Reason 3

To allow you to truly see how you feel at different levels of carbs and fat so you can find your unique carb threshold or the general amount of carbs you feel best consuming.

Here's an example of how to configure your macronutrient changes week by week. Calories are up to you, but if you have no idea where to start, a good starting point is:

  • For fat loss: bodyweight x 10 to 12
  • For weight maintenance: bodyweight x 13 to 15
  • For mass gain: bodyweight x 16 to 18

If you have a slower metabolism, hypothyroidism, are perimenopausal, or are over age sixty, you'll likely need fewer calories, so play with it until you find a spot where you experience some hunger at some point during the day, but it's tolerable, and you're slowly losing body fat.

If you're a fast metabolizer, have more muscle and/or are very active, you'll likely need more calories than what's indicated above. So find your sweet spot.

So now let's talk macros. This is what I recommend when transitioning off keto, which is generally about 60-70% fat, 30-40% protein (I always recommend a higher protein keto), and 5% carbs.

I like to immediately push people to 40% protein (and highly recommend resistance training as part of your plan), with fat and carbs as follows:

Week One

Percentage of total calories by macronutrient:

  • Protein: 40%
  • Fat: 40%
  • Carbs: 20%

Week Two

  • Protein: 40%
  • Fat: 35%
  • Carbs: 25%

Week Three

  • Protein: 40%
  • Fat: 30%
  • Carbs: 30%

Week Four

  • Protein: 40%
  • Fat: 25%
  • Carbs: 35%

Continue playing with percentages as needed. Don't go below 20% of total calories from fat, however. Your body needs it for hormone production, cellular health, and brain and nervous system health.

Keto has its seat at the nutritional table. It's a natural part of human metabolism. Going through a phase of keto is extremely helpful for achieving optimal metabolic flexibility. Once that's established, your body should be able to absolutely thrive on carbohydrates and easily transition into ketosis on an as-needed basis.

Editor's Note: This is an intriguing topic. If you'd like to learn more, check out Tara's book, Short-Term Keto: A 4-Week Plan to Find Your Unique Carb Threshold.

Short-Term Keto: A 4-Week Plan to Find Your Unique Carb Threshold
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    Impairment in Adults Aging with HIV: A Pilot Study. J Assoc Nurses AIDS Care. May-Jun 2020;31(3):312-324. PubMed.
  2. Greco T et al. Ketogenic Diet Decreases Oxidative Stress and Improves Mitochondrial Respiratory Complex Activity. J Cereb Blood Flow Metab. 2016 Sep;36(9):1603-13. PubMed.
  3. McClernon FJ et al. The Effects of a Low-Carbohydrate Ketogenic Diet and a Low-Fat Diet on Mood, Hunger, and Other Self-Reported Symptoms. Obesity. 2007;15(1):182–7. PubMed.
  4. Wood RJ et al. Carbohydrate Restriction Alters Lipoprotein Metabolism by Modifying VLDL, LDL, and HDL Subfraction Distribution and Size in Overweight Men. J Nutr. 2006 Feb;136(2):384-9. PubMed.
  5. Mensink RP et al. Effects of Dietary Fatty Acids and Carbohydrates on the Ratio of Serum Total to HDL Cholesterol and on Serum Lipids and Apolipoproteins: A Meta-Analysis of 60 Controlled Trials. Am J Clin Nutr. 2003 May;77(5):1146-55. PubMed.
  6. Westman EC et al. The Effect of a Low-Carbohydrate, Ketogenic Diet Versus a Low-Glycemic Index Diet on Glycemic Control in Type 2 Diabetes Mellitus. Nutr Metab (Lond). 2008 Dec 19;5:36. PubMed.
  7. Cheng CW et al. Ketone Body Signaling Mediates Intestinal Stem Cell Homeostasis and Adaptation to Diet. Cell. 2019 Aug 22;178(5):1115-1131.e15. PubMed.
  8. Włodarek D. Role of Ketogenic Diets in Neurodegenerative Diseases (Alzheimer's Disease and Parkinson's Disease). Nutrients. 2019 Jan 15;11(1):169. PubMed.
  9. Cabrera-Mulero A et al. Keto Microbiota: A Powerful Contributor to Host Disease Recovery. Rev Endocr Metab Disord. 2019;20(4):415–425. PubMed.
  10. Mavropoulos JC et al. The Effects of a Low-Carbohydrate, Ketogenic Diet on the Polycystic Ovary Syndrome: A Pilot Study. Nutr Metab (Lond). 2005 Dec 16;2:35. PubMed.
  11. Tan-Shalaby J. Ketogenic Diets and Cancer: Emerging Evidence. Fed Pract. 2017 Feb;34(Suppl 1):37S–42S. PMC.
  12. Gershuni VM et al. Nutritional Ketosis for Weight Management and Reversal of Metabolic Syndrome. Curr Nutr Rep. 2018 Sep;7(3):97-106. PubMed.

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