When You Aren’t What You Eat: Fats and the Keto Diet

Dr. Christopher McGowan
January 15, 2021

If someone told you one of the fastest ways to lose fat was to eat more fat, you might think they were crazy. As surprising as it sounds, especially after years of nutritionists telling us to cut down on dietary fat, losing weight by eating lots of high-fat food is exactly what the ketogenic diet is all about. Not all fats are created equal, though, and if you are going to start messing around with your diet, it pays to know what you are getting into. 

What is Fat, and What Role Does it Play in the Body?

Though it has been vilified by dietitians, fat is considered a macronutrient. Fat plays many important roles in keeping you healthy, such as helping your body absorb a wide range of fat-soluble nutrients from your food. You may be wanting to lose weight to get that beach body, but without fat in your diet you can’t absorb the vitamin D you get from a sunny day by the water. Vitamins A, E, and K also need a little help getting into your system, and healthy fats provide just the assistance required to break them down into forms your body can use. 

Fat in your diet also has the benefit of helping you feel full. This can be useful in helping to keep your overall calorie intake lower by helping you feel satisfied sooner. This is due in large part to how your body metabolises certain fats, and what happens to them after they get into your bloodstream.

One of the most important aspects of fat is in the energy it contains. When your body runs out of carbs and goes looking for something else to burn, it begins converting fat to energy for your cells. The breakdown of stored fat creates organic compounds called ketones that can be used as energy. This process is known as ketosis. 

The keto diet is designed to keep you in a state of ketosis as much of the time as possible. This is done by increasing your fat intake while cutting back on the carbs and sugars, which provide energy your body could also use. Short and medium chain fatty acids found in foods like butter, cream, and coconut oil travel to the liver once you have eaten them. In the liver, these fatty acids are converted to ketones quickly, giving your body the shortest route to the energy it needs. 

How is Keto Different from Other Low-Carb Diets?

Low-carb diets have been around for many years, and the goal of this kind of dieting is goading your body into burning fat. When you eat carb-heavy foods, you end up with higher amounts of glucose in your blood. This readily available energy source is great from your body’s perspective, but only if you are active enough to use it quickly. If you are not working out or maintaining an active lifestyle, all that extra blood sugar leads to elevated insulin levels as your body tries to stash the glucose for later. Since your body only has one way to store this cheap energy, the result is predictable: you end up gaining weight.

So, cutting the carbs but filling up on veggies, proteins, and healthy fats can still give your body the vitamins and minerals you need while lowering the high amount of blood sugar that comes from carbs. If planned properly, this diet can nudge your body into using the energy in stored fat to keep you going. 

Ketogenic diets take the low-carb logic to the extreme. In addition to cutting out the carbs, keto diets add in a high amount of dietary fat for energy. This may seem counterintuitive at first, but by introducing fats your body can convert to ketones, you can induce a state of ketosis to kickstart the fat burn, which could get you dropping pounds fast. 

Unhealthy Fats to Avoid on a Keto Diet

We have established that, as counterintuitive as it may seem, eating more healthy fat can help weight loss. “Healthy” is the important part of that term, though. Not all fats are created equal. In a keto diet you are going to be getting as much of your energy from fats as possible, which means you are going to be taking in far more dietary fat than you are used to, but this also means you could end up taking in a harmful amount of the wrong fats if you choose them poorly.

Too much of a good thing might still be bad for you, but too much of a bad thing most certainly is. Keeping your body in ketosis is a difficult process for many people used to eating a standard American diet. Doing it while avoiding unhealthy fats is even harder. You will have to be very careful and selective about exactly what you are eating to ensure you get the health benefits you are looking for without increasing the risk of heart attacks or liver problems that could come from eating the wrong kind of fats.

To start with, let’s look at the unhealthy fats you should be avoiding no matter what diet you are on. Trans fats are the worst offenders here. These fats are found in processed food of all kinds and are typically introduced as hydrogenated oils used to preserve processed food so it stays fresh on the shelf. Research has consistently shown, however, that these fats are very, very damaging to the body. No matter how many grams of net carbs you are eating, trans fats are linked to high rates of cardiovascular disease and should be avoided.

There are other sources of fats that are not quite as nefarious as trans fats, but are still probably not good for you. While vegetable oils were identified in the past as supposedly healthier alternatives to other full-fat cooking oils, we now know they are not as beneficial as we previously thought. This is particularly true if you are cooking at high heat, which can cause vegetable oil to break down in ways that are not healthy for you. 

When it comes to cooking, even some healthier fats like olive and avocado oil are still not ideal if you are using particularly high temperatures. Cooking with a saturated fat such as butter or ghee will stand up to high temperatures better without breaking down into more volatile compounds. 

Healthy Fats for Ketosis

When it comes to healthy fats, on the other hand, there is a lot more to consider. The first thing to remember is that the old advice to avoid saturated fats no longer holds as true as it once did. If you are on a keto or other low carb diet, taking in a wide range of healthy fats is going to be essential to staying healthy. 

Broadly speaking, healthy fats are broken down into two categories: saturated fats and unsaturated fats. These include saturated fats, monounsaturated fats, and polyunsaturated fats. Each of these categories predominate in different foods, though all fatty foods contain small amounts of all varieties of fat.

Saturated Fats

If you like dairy, you are in luck when it comes to saturated fats. Cheeses, cream, and butter are all found in this category, as well as items less common in contemporary Western cuisine like ghee and lard. Other items in this category include:

  • cheese
  • lard
  • coconut oil
  • full-fat cream
  • butter 
  • ghee

Monounsaturated Fats

This group of fats contains some of the most useful fats in terms of weight loss. Medium-chain triglycerides are converted quickly by the liver into ketones, which is very useful if you are looking to stay in ketosis. This is a category that contains many of the oils used in cooking and salad dressings, so individuals looking to increase their overall fat intake can find plenty of options here. A few of the most common sources of monounsaturated fats are from foods like:

  • olive oil (and the olives they come from)
  • macadamia oil and macadamia nuts
  • various nuts, including pecans, almonds, peanuts, and cashews
  • Tallow and lard
  • MCT oil

Polyunsaturated Fats

Omega-3 fatty acids are compounds that are noted for health benefits even outside of the low-carb world. For the carnivores among us, these healthy fats are found in some of the tastiest items on the menu, particularly in seafood. Fatty fish and properly raised steak or lamb are great sources of these fats, but they are not the only sources of these fats. Those on a vegetarian diet also have options in the form of various seeds or oils. A quick list of the best sources are:

  • fish such as salmon, mackerel, and sardines
  • grass-fed red meat 
  • valnuts
  • vegetable oils
  • flaxseeds
  • chia seeds

How do I Increase My Fat Intake on Keto?

Increasing your fat intake while on a keto diet is going to mean doing some things that would have seemed laughable or even dangerous before. Rather than a bit of creamer in your coffee, you might want to consider a spoonful of butter. Many people make so-called “fat bombs” out of a mixture of high-fat, low-carb ingredients like nut butters, coconut cream, and flavorings like cocoa powder. Eating full-fat dips made with avocados, olive oils, tzatziki, and other high fat ingredients also help.

Is it Possible to Not Eat Enough Fat on Keto?

Keto diets involve managing a careful balance of biological processes, and it is possible to get it wrong. You need to be very aware of your starting body weight, net-carb intake from all food sources, and the number of grams of protein you are consuming. Getting this balance wrong could lead you to consuming too little fat. This can make it harder for your body to stay in ketosis, as well as put you at risk of nutrient deficiencies from not being able to absorb fat-soluble vitamins.

Keeping a meal plan and being very selective about how you are getting fat in your diet is essential to keeping your diet heart-healthy. Taking in large amounts of fat only works if you are keeping your body in ketosis, and that means keeping a very strict eye on your net carb intake. Even small additions of things like sugar in your coffee can be enough to allow your body to drop out of ketosis. 

Alternative sweeteners such as stevia are popular with the keto diet crowd, and for good reason. Stevia is not processed by your body in the same way as traditional sugar, and it does not contribute to a rise in blood sugar. You should still use it sparingly, though, if you are serious about a keto diet being your path to weight loss. 

Another thing to be wary of is pairing low-carb with a low-fat diet. If you are not giving your body enough carbs to use as fuel, you need to be replacing it with something. Planned appropriately, a low-carb, high-fat menu can make for a healthy diet, but only if you are paying attention to the grams of fat you are getting from various sources. 

Cholesterol and Ketosis

Contrary to much of the nutritional advice given out over the last several decades, we now know that the amount of cholesterol in your food has less to do with the levels of cholesterol in your blood. Your body produces this waxy substance on its own, and the interaction between sugar, which causes low-level inflammation throughout the body, and cholesterol, is of more concern than how many eggs you eat in a day. 

That said, keeping unhealthy fats out of your diet is extremely important. The aforementioned trans fats are again to blame here. A diet high in these processed fats can lead to a rise in LDL cholesterol and a drop in the healthier HDL levels. This can have profoundly negative effects on your heart health, raising your risk of a heart disease. 

Planning for Success with High Fat Diets

So, you are going to start a keto diet, have sorted out where you will be getting your proteins from and have said a sad goodbye to the carbohydrates you know and love. Now comes the important question: how will you get enough fat in your diet without doing more harm than good?

Any diet takes planning, and keto diets are no exception. Staying on track will take discipline and careful attention to what you are eating on a daily basis. Many people find it difficult, especially early on in a diet to stick to a meal plan that is quite different from what they are used to eating. 

It is important to remember that keto may not be for you. Not every diet is a good idea for everyone, and popularity is no reason to pick a diet that won’t fit your lifestyle and medical needs. Keto is an involved and specific diet that can cause a lot of harm to your body if you do it wrong. Consulting your doctor and possibly a dietitian before you climb on the high-fat bandwagon is a good idea.

At True You Weight Loss, our medical nutrition therapy program exists to help people make life-long changes in their diet and lifestyle. Not everyone who is looking to lose weight can do it on their own, and we want to be there to help. If you are considering keto, or just want to know more about how to get rid of excess body weight for good, request a consultation with True You today.

Dr. Christopher McGowan
Dr. Christopher McGowan

Dr. Christopher McGowan, MD, a leader in endobariatrics, specializes in non-surgical obesity treatments and is triple-board-certified in Internal Medicine, Gastroenterology, and Obesity Medicine. Renowned for pioneering endoscopic sleeve gastroplasty (ESG) with over 2,000 procedures, his global influence and research contributions define him as a top expert.

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