Keto Diet

July 5, 2026 · John Bergeron, MD

Few diets have stuck in the mainstream the way keto has. The ketogenic diet is a very low carb, high fat, moderate protein plan designed to shift your body into a metabolic state called ketosis, where it burns fat for fuel instead of carbohydrates. It started as a medical diet, originally used to control epilepsy in children who did not respond to medication, and weight loss turned out to be a useful side effect.

What keeps keto relevant is that it does something measurable to appetite and blood sugar, which is the same territory modern weight loss medicine works in. Now that GLP-1 medications are part of the picture, the interesting question is not keto versus everything else, but how a ketogenic approach fits alongside medical treatment. Below is how keto works, what you can and cannot eat, an honest look at the pros and cons, and how it pairs with GLP-1 therapy.

What is the keto diet, and how does ketosis work?

On a normal diet, your body runs on glucose, the sugar it pulls from carbohydrates. Keto cuts carbs low enough that glucose runs short, so the body switches to burning fat instead. The liver turns that fat into ketones, which your muscles and organs use for energy. That switch is ketosis, and it usually begins within the first week on the diet.

The whole plan hinges on hitting specific macronutrient targets. The typical keto breakdown is roughly:

Fat: 60 to 75 percent of calories
Protein: 15 to 30 percent
Carbohydrates: 5 to 10 percent, usually about 20 to 25 grams of net carbs per day (total carbs minus fiber)

In some ways keto resembles the Atkins Diet, since both are low carb, and it shares the Mediterranean diet preference for fats like olive oil, nuts, and avocado. Where keto goes further is the sheer amount of fat it asks for, which is the part most people find genuinely hard to do well.

What you can eat (and what to avoid)

Foods you eat on keto

Meat, poultry, and fish
Eggs
Leafy greens and non-starchy vegetables
Avocados
Olive oil and coconut oil, olives, nuts, and seeds
Full-fat dairy: cheese, cream, butter, plain yogurt
Berries in small amounts
Dark chocolate (high cocoa, low sugar)

Foods you avoid on keto

Bread, pasta, and grains
Sugar, including honey and agave
Beans and legumes
Starchy vegetables like potatoes
Higher-sugar fruit like bananas and oranges

The tricky part is that carbs hide almost everywhere, so a 20 to 25 gram daily limit is harder than it sounds. A single apple is about 14 net carbs. That is why berries make the list (high fiber) while most other fruit does not. It is also worth a caution in the other direction: keto is not a license to eat unlimited fat of any kind. Butter and mayonnaise are not the same as olive oil and avocado, so the quality of the fat still matters.

The possible benefits of keto

Weight loss. This is the main draw, and people do tend to lose weight consistently when they stay within the macros. Cutting refined carbs and added sugar removes a lot of easy calories.

Fewer cravings. Many people find that higher fat and protein, with very little sugar, blunts appetite and reduces cravings over time.

Better blood sugar and cholesterol markers. Some research links low-carb eating to improved triglycerides and HDL (the “good” cholesterol), and steadier blood sugar. The evidence is encouraging rather than settled, so treat it as a possible benefit, not a guarantee.

PCOS symptoms. Early studies suggest women with polycystic ovary syndrome may see improved insulin levels and hormone balance on a lower-carb diet, though more research is needed.

Does keto work? An honest look

Keto works for many people, with the usual caveat that applies to every diet.

What it does well. Steady weight loss, reduced cravings, and improvements in some metabolic markers are real for a lot of people who stick with it. For the right person it can be effective.

Where it falls short. The first week or two often brings fatigue, headaches, and irritability, the so-called “keto flu,” as your body adjusts and sheds water and electrolytes. Hitting 60 to 75 percent of calories from fat, and doing it with healthy fats, is genuinely difficult to sustain. Keto is restrictive and socially awkward, and like any diet, the weight tends to return when the plan stops. There is also an important safety point: for people with diabetes, high ketone levels can lead to diabetic ketoacidosis, a life-threatening condition, so keto should never be started by anyone on diabetes medication without a doctor’s involvement.

The honest throughline is the same one that runs through every diet: they rarely fail because the mechanism is wrong. They fail because willpower alone does not hold against biology over the long term. That is the gap medical weight loss is built to close.

Keto and GLP-1 medications

Keto and GLP-1 therapy are both powerful appetite and blood sugar levers, which makes them a promising pairing and also the reason to be careful. GLP-1 medications, the class that includes semaglutide, tirzepatide, and liraglutide, reduce hunger and slow digestion. Keto lowers appetite and blood sugar from the food side. Stack them without oversight and the combined effect can be too much, which is exactly why we manage them together.

Protein comes first. GLP-1 medications already cut appetite hard. Add a restrictive keto plan on top and it becomes very easy to eat too little overall, which risks losing muscle along with fat. Prioritizing adequate protein protects lean mass while you lose weight, and it is one of the first things we watch.

Blood sugar and ketoacidosis risk. Both keto and GLP-1 medications lower blood sugar, and for anyone on diabetes medication that overlap needs close monitoring. The diabetic ketoacidosis risk that applies to keto alone deserves even more attention when a medication is in the mix, so this combination truly belongs under medical supervision.

Electrolytes and the keto flu. The early keto adjustment already flushes fluids and electrolytes, and reduced intake on a GLP-1 can compound it. Staying ahead of hydration and electrolytes prevents much of the rough patch.

Managed properly, keto and a GLP-1 can reinforce each other. Left unmanaged, the same overlap that makes them effective is what makes them risky, which is the whole reason we do it with oversight rather than on our own.

Is keto right for you?

Keto can be a strong fit if you do well with structure and do not have a condition that makes it unsafe, but it is demanding, and it is not the only path. If it sounds too strict, there are plenty of other low-carb options that work well over the long term, sometimes with less dramatic early results but easier staying power. And whatever eating pattern you choose, the diet is only one piece. What decides whether the weight stays off is having medical support that adapts the plan to your body over time.

At Houston Weight Loss Center, we have practiced metabolic medicine since 1996, and today that means pairing sound nutrition with GLP-1 therapy and physician oversight, not one or the other. If you are considering keto, or wondering how it fits with a GLP-1 medication, talk with our team in Houston, Katy, and Webster about a plan that is both effective and safe.