What is the KetoFlex 12/3 Diet?

by Amylee Amos MS, RDN, IFMCPNutrition

The KetoFlex 12/3 Diet is a nutrition plan designed to help optimize brain health by downregulating the drivers of cognitive decline and upregulating factors that increase synaptic and neuronal growth. Drivers of cognitive decline including inflammation, insulin resistance, and toxicity are heavily influenced by our diet. The western diet, which is now consumed by much of the world, promotes these harmful metabolic states which contribute to disease. However the foods we eat can have the opposite effect too, and rather than promoting disease, promote healthspan and longevity. Food and nutrition can be leveraged to optimize our health and, in particular, optimize our brain health by upregulating factors that create the growth of new brain cells and preserve the integrity of the brain cells we already have. The KetoFlex 12/3 Diet is designed to do just that. 

What is the KetoFlex 12/3 Diet?

The “keto” of the KetoFlex 12/3 Diet refers to ketosis. The KetoFlex 12/3 Diet is formulated to help individuals get into a state of mild ketosis because ketosis has many benefits for cognition. Ketosis refers to the natural physiologic state in which the body produces ketone bodies, a byproduct of fat metabolism that serve as an excellent fuel source of the brain. The level of ketosis needed to promote brain health is quite low compared to the true ketogenic diet, which is why there are so many misconceptions surrounding ketogenic diets

The “flex” of the KetoFlex 12/3 Diet refers to two different concepts. First, “flex” refers to metabolic flexibility, or the ability of the body to fluidly transition between a carbohydrate based metabolism and a fat based metabolism. Achieving metabolic flexibility is absolutely essential to preventing and reversing chronic disease. Following the KetoFlex 12/3 Diet helps individuals naturally achieve this optimal metabolic state. Additionally, “flex” refers to the flexibility of the KetoFlex 12/3 Diet to either include or not include small amounts of animal products. Overall, the KetoFlex 12/3 Diet is heavily plant based, which means that the vast majority of foods included in the diet are plant foods. However, some people choose to include small amounts of high quality animal products. Others following this diet choose to do so without any animal products at all. This flexibility is incredibly important as it promotes better compliance and individualization. 

Finally, the “12/3” refers to intermittent fasting and specifically to time restricted eating. The KetoFlex 12/3 Diet suggests an eating window of no longer than 12 hours, which means that you fast (not eat or drink anything other than water) for 12 hours overnight. The “3” refers to stopping all eating and drinking at least 3 hours before going to bed. These simple fasts help reestablish insulin sensitivity and allow the brain valuable time to “clean up” aggregated plaques and proteins that have accumulated in the brain throughout the day. 

What Foods are Emphasized on the KetoFlex 12/3 Diet?

Non-Starchy Vegetables

The foundation of the diet is non-starchy vegetables. These vegetables, including leafy greens, colorful vegetables, cruciferous vegetables, and others are rich in vitamins, minerals, fiber, and phytonutrients that are essential for optimal health. Eating these vegetables in large quantities optimize health by regulating blood glucose levels, aiding in detoxification, and providing necessary trophic factors for the brain. 

Healthy Fats

Healthy fats such as those from avocado, wild caught fatty fish, extra virgin olive oil, olives, nuts, and seeds are emphasized because they encourage mild ketosis, which fuels the brain. These plant based sources of fats are preferred because they reduce inflammation. Saturated fats, such as those from animal products and coconut oil need to be avoided or reduced in those who carry the genetic variant ApoE4. Additionally, they are needed to promote the health of our cellular membranes which act as mediators of cellular exchange and communication. 

Gut Supporting Foods

The KetoFLex 12/3 Diet emphasizes foods that support and regulate good gut health. This includes prebiotic foods such as vegetables and resistant starches, and probiotic foods such as those with live cultures of bacteria. Some excellent sources of prebiotic foods include Jerusalem artichokes, jicama, asparagus, flaxseed, and onions. Resistant starches such as legumes, sweet potato, yams, green banana, and taro are particularly beneficial, but are only recommended once you are insulin sensitive and have optimal glycemic control. Probiotic foods actually contain the healthful bacteria itself. These help populate the gut with microbes that promote health, which also physically block the colonization of harmful bacterial populations. Some great probiotic foods include sauerkraut, kimchi, brined olives without vinegar, fermented vegetables, and unsweetened non-dairy yogurt. 

Other foods to prioritize include foods that increase BDNF, adequate protein rich foods such as wild caught seafood, tempeh, and pasture raised eggs, phytonutrient rich, low glycemic fruits such as blueberries, blackberries, and raspberries. 

What Foods are Not Included on the KetoFlex 12/3 Diet?

Processed Foods and Added Sugars

Processed foods such as packaged crackers, chips, cookies, cakes, sweets, pizza, french fries, and fried foods are devoid of nutrients and rich in calories. The western diet, which is high in processed foods, is a major driver of inflammation, glycotoxicity, and oxidative stress, which also happen to be the underlying contributors to Alzheimer’s disease. Processed foods and the dramatic increase in their consumption has resulted in what is being called a nutrition transition, where we are seeing more and more malnourished individuals who are overweight and obese. 

Gluten Containing Grains 

Gluten, which is found in grains such as wheat, barley, semolina, rye, and others, is removed from the diet because it can contribute to inflammation by increasing intestinal permeability (1). This eliminates foods such as pasta, bread, flour tortillas, pretzels, and baked goods. While gluten may not be problematic for all individuals, for those trying to reverse or prevent Alzheimer’s disease, consumption of foods that are known to increase intestinal permeability and inflame the gut is risky and destructive. 

Many who begin the KetoFlex 12/3 Diet initially remove all grains from their diet. In those that are very metabolically inflexible, it can be helpful to remove all grains to allow for a higher percentage of total calories from fat and to reduce the amount of starchy carbohydrates. 


Dairy products such as milk, yogurt, and cheese are removed from the KetoFlex 12/3 Diet. Among other issues, dairy products are problematic because they upregulate cellular growth pathways that contribute to disease. In particular, conventional dairy products are especially harmful because they contain hormones and endocrine disrupting chemicals that disrupt our natural hormone cycles. For those who do choose to continue to eat small amounts of dairy, sheep and goat’s milk dairy is recommended over cow’s milk dairy because they contain a compound called casein A2, which is less inflammatory than the casein A1 found in nearly all cow milk dairy products. 

Other foods to reduce or eliminate include animal meat, especially conventionally raised animal meat, processed meats, fast food, and artificial sweeteners. 

How to Follow the KetoFlex 12/3 Diet

This synopsis of the KetoFlex 12/3 Diet just barely skims the surface of all there is to know and implement. There are so many other important details and areas for personalization. To fully implement the KetoFlex 12/3 Diet, you need a program designed to walk you through each part of this way of eating. Even something as simple as the sourcing of foods can be extremely complex- for example, organic versus conventional produce, pasture raised versus free range eggs, wild caught versus farmed fish, or organic versus non-GMO products. You also need access to a qualified dietitian nutritionist who specializes in this nutrition plan to help you personalize the diet to meet your genetic, biochemical, and lifestyle needs. The Amos Institute Cognitive Health Program covers all of these topics and so much more, as well as offers you the ability to personalize the program to meet your unique needs. Sign up today!


De Punder K, Pruimboom L. The Dietary Intake of Wheat and other Cereal Grains and Their Role in Inflammation. Nutrients. 2013; 5(3):771-787. https://doi.org/10.3390/nu5030771