Weight Loss with the Keto Diet: Does it Last?

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Written by Melissa Mitri, MS, RD

The ketogenic diet, ketone diet, or “keto” for short, remains a popular diet, but it is not as much as it used to be. Why is that, and does it lead to permanent weight loss? Here I’ll be talking about the pros and cons of keto, weight loss with the keto diet, and my client’s experiences.

You probably know at least one person who has tried keto. You may be asking yourself “well they lost weight and it seemed to work for them, so it probably works right?” It may have worked for them, but does keto work for everyone? As I always say, we are all unique and there is not a single diet out there that works for everyone.

Read on to learn about the benefits of the keto diet and if it will help you lose weight long-term.

What is the ketogenic diet?

The keto or ketogenic diet is a very low-carbohydrate, high-fat diet that is moderate in protein. The term ketogenic comes from the word “ketosis”, which is a reaction that happens in your body when it doesn’t have enough carbs. Instead of burning carbs for fuel, your body burns fat. This produces a substance called ketones.

When these ketones are produced, many experience the benefits of a ketogenic diet such as fat-burning effects, decreased appetite, and lower blood sugar levels.

The keto diet was traditionally used as a diet treatment for epilepsy, in which it was effective for many people. But over the last several years it has gained in popularity as a weight loss diet.

What are ketones exactly?

Ketones are an alternative fuel that your body produces when it doesn’t have enough carbs for energy. Instead, the liver breaks down the stored fat in your body. Ketones have also been seen to increase satiety and reduce appetite, and therefore may make it easy for some people to stick to it.

Here are the core features of the keto diet:

Very high in fat – A keto diet is about 70-80% fat, where you are eating at least 100-150 grams of total fat per day. This requires conscious effort and does not always happen automatically.

Very low in carbs – Only 5-10% of your calories on keto come from carbs. This ends up being less than 50 grams of carbs per day, and sometimes as low as only 20 grams.

Moderate in protein – A keto diet is considered “moderate” in protein, where 10-20% of your calories come from protein. The exact amount of protein you need can vary based on different factors such as your age and activity level.

The premise of the keto diet for weight loss is that you deprive your body of glucose (which comes from carbs in your diet). In doing this, your body then begins to break down your fat stores for fuel.  

If your carb intake is low enough and your protein intake is moderate (but not too much), your body will transition to a state of “ketogenesis” where it burns more calories from the breakdown of your food. 

Before deciding on whether to try it, it’s important first to know what you can and can’t eat on a keto diet.

What can you eat on Keto?

On a keto diet, fats are promoted most heavily, then protein, then carbs.

High fat – oils, butter, lard, avocado, coconut, some nuts and seeds, meat and poultry

Moderate Protein – grass-fed beef, free-range poultry, pork, bacon, wild-caught fish, organ meats, eggs, tofu, some nuts, and seeds

Very Low Carb – 30-50 grams per day – berries, limited amount of dairy

Food List for the Keto Diet

Here is a keto food list of allowed foods:

• Meat – pork, chicken, turkey, beef, fish
• Eggs
• Fruit – avocados, berries
• Vegetables – cauliflower, green beans, spinach, zucchini, broccoli, bell peppers
• Dairy – cheese, cottage cheese, plain Greek yogurt, sour cream, heavy cream
• Other foods – dark chocolate, olive oil, nuts and seeds, unsweetened plant-based milks, alternative flours like almond or coconut flour, unsweetened coffee or tea

Here is a list of what you can’t eat on keto:

Pros and Cons of the Keto Diet

Here are the biggest pros and cons of the keto diet to decide if it is for you.

Pros

• Produces fast weight loss
• Improves satiety
• Burns belly fat
• May improve health markers
• Many resources available

Produces fast weight loss

One of the biggest appeals of the keto diet is the possibility of quick weight loss. Most people that follow keto tend to lose weight quickly in the beginning, which can be motivating.

There are a few potential reasons for the initial quick weight loss with keto:

• Water weight loss – In the first few weeks on a keto diet, the weight you lose is primarily water weight. This is because when you consume a very low-carb diet, your body rids its body of water. The 5-10 lb weight loss you may see in these early weeks is exciting, but it typically levels off shortly after.
• Increased fat-burning efficiency – Some research points to the possibility that following a keto-style diet offers a “metabolic advantage”. It is said that it preferentially burns fat in the body. Typically, your body burns carbohydrates or glucose for fuel, but if your diet is very low in carbs, it may burn your body fat instead.
• Increased thermic effect of food – The thermic effect of food, or TEF, is the increase in metabolic rate that occurs in the body after consuming a particular type of food. High-protein foods produce a higher TEF, which may help you burn more calories after eating. This can increase your metabolism over time. Since the keto diet is fairly high in protein, this is one proposed mechanism for how it helps you lose weight.

Improves Satiety

Many studies have shown those following a keto diet report feeling less hungry. The keto diet is very high in fat and moderate in protein. Both fat and protein are very satisfying nutrients compared to carbs.

However, the ketones produced themselves may reduce the appetite. In other words, when your body transitions to a state of ketosis, these ketones can act as an appetite suppressant.

Burns Belly Fat

There is some evidence regarding the keto diet for burning belly fat. This may be mostly due to the fact that keto is a very low-carb diet. Low-carb diets have been seen in a few studies to lead to more abdominal fat loss than traditional low-calorie diets.

May Improve Health Markers

The keto diet may also improve other non-weight aspects of health. Some examples include decreased triglycerides, lower LDL (the “bad” cholesterol) levels, lower blood glucose (blood sugar) levels, and increased HDL (the “good” cholesterol) levels.

It is important to note that while these benefits have been seen, they have only been studied for up to 24 weeks. Therefore it is unknown if these benefits would continue in the long term.

Many Resources Available

If you’re looking to start the keto diet, there is a wealth of resources available. Upon a quick Google search, you’ll come across an array of keto resources. These include keto recipes, keto meal plans, keto diet books, and keto diet tips on how to get started.

When the going gets tough this can make things easier and help you find answers to any questions about the diet.

There are even keto meal delivery services out there that can provide keto-friendly meals to fit your diet goals.

Cons

While there are some pros to the keto diet, there are equally some surefire cons:

• Restrictive
• Not sustainable
• Expensive
• Possible side effects
• Nutritional deficiencies

Restrictive

The keto diet is restrictive in nature and can be difficult to follow. It also restricts many healthy foods that you may be accustomed to eating. This can leave you feeling unsatisfied. However, some people report feeling less hungry on it, like a few of my clients, so not everyone’s experience is the same.

Many foods that are not allowed on keto are also nutritious foods such as whole grains, beans, and dairy that can assist with weight loss.

Additionally, research has shown that restrictive diets can increase the likelihood of overeating and eating disorders.

Not Sustainable

Because the keto diet is restrictive and difficult to follow in social settings, it’s not very sustainable for most people. It requires a great deal of meal prepping and planning on a daily basis. It also may be even more difficult when it comes to eating at a social gathering or restaurant, where carbohydrate-containing meals abound.

And if a diet is not sustainable, it is more likely that you will not be able to follow it long-term and will regain the weight back. This is not your fault, this is the fault of the unrealistic diet restrictions themselves!

Expensive

Going keto can be expensive, especially if you opt for all the healthy fat sources such as coconut, MCT, and avocado oils. These oils can be hard to find and are significantly more expensive per serving than the typical canola or olive oils (which, by the way, are also super healthy).

Many low-cost nutritious foods like beans, legumes, and whole grains are not allowed on keto. On the contrary, higher-cost meats and cheeses are more prevalent.

If you’re on a tight budget – keto may not be for you.

Possible Side Effects

There are several possible keto diet side effects to note that you may experience, especially in the first few weeks. These early symptoms are also known as the “keto flu” and include symptoms such as :

• Fatigue
• Irritability
• Brain Fog
• Exercise Intolerance/Reduced Stamina
• Digestive Upset
• Insomnia
• Light-headedness
• Weakness
• Nausea

Some may only experience these side effects during the first 1-2 weeks, while some may not at all. For some, however, the body doesn’t adjust even in the long term. If that’s the case, this may be a telltale sign the diet isn’t for you.

Nutritional Deficiencies

Nutritional deficiencies are possible on the keto diet. Because you are avoiding certain food groups, nutrients such as vitamins C and D may be lacking. If you are thinking about going keto, consult with your medical doctor or a Registered Dietitian to help you meet your nutrition needs.

What can I expect if I’m starting a keto diet?

If you’re considering the keto diet for weight loss, there are a few important things to note before you start.

Weeks 1-3: This is the adjustment period. Some people adjust fine, while others may experience side effects known as the “keto flu” such as nausea, fatigue, brain fog, or weakness.

This is the result of sodium and fluid rapidly exiting your body. This is often the body’s response to a very low carbohydrate diet. The large shift in your body’s metabolism can cause these unpleasant symptoms.

This initial weight loss of anywhere from 5-10 pounds can be motivating and can keep you going. Many of my clients who were seeking that “jumpstart” were very happy with these quick results.

Weeks 3 and beyond: If you stick to the diet, weight loss may continue for another 4-5 months. At this point, some of it starts to level off.

This is common not just on the keto diet, but on many calorie-restricted diets. It can happen for many reasons but is often because your body at its new weight adjusted to a lower calorie intake.

Maybe you’re happy with how far you came and are okay with staying at your current weight, or maybe you want to lose more. Either way, speaking to a professional like a Registered Dietitian can help you figure out the next steps to take.

So can you lose weight on the keto diet?

In short – yes. Many people successfully lose weight on keto, but the caveat is, like most restrictive diets, it likely doesn’t last.

If you can get over the keto flu hump, you may feel satisfied and lose weight fairly quickly during this time.

However, there are studies that show that after a few months, the weight may start creeping back up. The weight loss slows, hunger and cravings return with a vengeance,(often more than prior to following keto) and it becomes more difficult to adhere to. This then creates that vicious diet-binge cycle.

I’ve seen this in many of my clients who have shared their past keto diet experiences with me. This typically worsens their overall relationship with their food. Not to mention this can be super frustrating when you initially are so motivated and seeing results, and then all of a sudden you feel like you’re going backward.

What the keto diet research says

According to much of the research, keto can help you lose weight. However, most of the research on the keto diet has been done up to a 24-week, or a 6-month timeframe. In regards to long-term weight loss results, the keto diet has been seen to show similar results to a traditional low-calorie diet.

Therefore, there is nothing magical about keto and it is a short-term fix. Eventually, you will probably want to add many of the restricted foods back into your diet or will need to if you become deficient. Then, the weight will start to creep back up.

It is questionable how long keto can realistically be followed long-term.  Restriction can be done temporarily, especially when there is more internal motivation at the beginning of your weight loss journey.  But once you hit a plateau or weight loss slows, it becomes more difficult to stay motivated. 

The newest research reviews covering several studies in the past 2-3 years show the following:

• The keto diet can be effective for weight loss and changing body composition favorably (in other words, losing fat and gaining or maintaining muscle).
• Serious side effects of the keto diet are rare.
• Many people losing weight on keto diets were also on very low-calorie diets. This may have been the main driver of weight loss, not the diet composition itself.
• More studies are needed to determine how effective it is long-term, its sustainability, and any potential risks further down the road.

Following the keto diet puts you at risk for nutritional deficiencies such as magnesium, potassium, and vitamins C and D. It also can cause constipation and digestive issues as it is limited in foods that are natural fiber sources like fruits, beans, and whole grains.

On the other hand, even though the keto diet is very high in fat, it may actually improve cholesterol levels. This may be a result of its ability to burn fat and result in weight loss.

What My Clients and Colleagues Had to Say

My experience with clients

I have had several clients who have followed a keto diet before working with me or have wanted to start one while working together. Most of my clients who followed it before working with me gained much of the weight back, and then some.

Many of them found it hard to stick to after a few months and was the primary reason why they came off of it.

I had a few clients who followed a modified keto diet, which was still considered low carb but not nearly as low carb as the traditional version. I like to think that any diet can be modified and tailored to the individual, especially if the traditional version is not working for them.

A couple of my clients who followed a modified keto diet did better and felt more satisfied.

My colleagues’ experiences

“In my experience with clients, the keto diet is largely unsustainable. Inevitably, my clients have seen good success at first which gets them excited about the diet. However, they find after the honeymoon period wears off, they are typically burned out and missed their favorite foods.

For the folks where I have seen it work long-term, they naturally do not crave carbs and don’t miss them when they cut them out. If that’s not you, keto is probably not realistic!

At its worst, I have seen the keto diet create incredibly disordered thoughts and behaviors with food and create binge/restrict cycles in people.” – Caroline Thomason, RD CDCES, a northern Virginia- based dietitian who helps women stop dieting and find confidence with food.

“I had a female client who had type 2 diabetes and when I began working with her she said that she had lost a lot of weight doing keto the year prior. However, on Thanksgiving day 2021, she reported she went “off the rails” and after that, she gained all the weight back through the holidays.

This year in 2022 after working with me for a few months she was on a more balanced nutrition plan entering the holiday season. She was able to moderate her intake of carbs/sweets over the holidays without going “overboard”. I explained to her that she is no longer in a restrictive mindset which can lead to overeating/binges but rather in an abundance mindset.

Now she balances her meal plates and snacks with whole grains, lean protein, veggies, and healthy fats. She allows herself to have sweets when craving them in small portions combined with protein and healthy fats. She has been able to lower her HgbA1c and feels so more energized.“- Gwen Johnson, RD, LDN of Sage Nutrition Solutions.

I tried the keto diet to lose weight so I could better my chances of conceiving. I’ve been obese all my life and thought why not give it it a try as my Dr. suggested weight loss after a miscarriage. With a personal trainer and keto I lost about 20 lbs in about 3 months.

However, it all came quickly back, and then some after I stopped doing keto and now find it even harder to drop weight. One of the biggest obstacles is adhering to the diet and the lack of credible material on keto for weight loss. In addition, constipation is common and supplementation is needed since you’re cutting out a lot of foods from fruits, vegetables, and almost all grains.” –Mary Dutta RD, LD

Many of my clients have had similar experiences, and when it comes down to it, you have to know yourself. If you feel better with less carbs and are satisfied, a modified keto diet may be more achievable. But if you find yourself craving what you can’t have, keto is likely not for you.

Who should not follow keto?

Even though I would not recommend keto in general to my clients, there are a few specific instances where a keto diet is contraindicated.

You have an eating disorder or a history of disordered eating

The keto diet restricts many foods and puts foods into categories of good and bad. This type of thinking and categorizing of foods only increases the chances of disordered eating behaviors.  

You are pregnant, trying to become pregnant, or breastfeeding

I would also not recommend this diet to anyone who is pregnant, as there is no research on the safety of this during pregnancy. During pregnancy and especially if you have morning sickness, carbs, and starchy foods often are much better tolerated and are all you can keep down.  

You also need a balanced diet during pregnancy with plenty of fruits and vegetables, many of which are restricted on the keto diet.

When trying to conceive you also need to ensure you’re getting all of the nourishment your body needs, as is the case during breastfeeding as well.

You’re an athlete or are very active

If you’re an endurance athlete or just very active, you need carbs. Restricting them will hurt your performance, lead to cravings, and can put you at risk for low blood sugar. Carbs (i.e. glucose) are your body’s preferred source of fuel during physical activity, and therefore limiting them is not in your best interest.

Sample 1-Day Keto Meal Plan:

If you are not in one of the above categories and decide to give the keto diet a try, here is a 1-day keto meal plan to get you started.

Breakfast: Smoothie with almond milk, leafy greens, almond butter, and protein powder

Morning Snack: 2 hard-boiled eggs

Lunch: Chicken tenders made with almond flour on a bed of greens with cucumber and goat cheese

Afternoon Snack: A handful of walnuts with a quarter cup of berries

Dinner: Grilled beef kebabs with peppers and sauteed broccoli

The Bottom Line – Weight Loss with the Keto Diet

When it comes down to it, I wouldn’t recommend a keto diet to most people and don’t typically recommend it to my clients. However, I have had clients for whom we employed a “modified keto” approach to weight loss. This works best for those who do well or generally feel better on lower-carb diets.

If you are following a keto diet or thinking about starting the keto diet, I encourage you to ask questions. Do the research and seek the advice of your doctor and a Registered Dietitian. No matter what diet you choose to follow, it has to be sustainable.

Lastly, getting to the root of your eating habits and your own internal motivators is paramount to achieving weight loss and keeping it off.

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