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Home » OSL Blog » The Keto Diet Basics: Why You Must Eat Fat to Burn Fat

The Keto Diet Basics: Why You Must Eat Fat to Burn Fat

May 27, 2019

When was the last time you ate sour cream, butter, or mayo? What about bacon or guacamole with parmesan on top? Believe it or not, these fatty foods can actually help you slim down. The key is to have a good understanding of the keto diet basics and follow the rules.

The ketogenic diet is one of the few weight loss plans backed up by science. Clinical evidence shows that it helps reduces body fat mass, improves blood lipids, and lowers blood sugar levels. Health professionals worldwide prescribe it to obese and overweight patients. It’s also a popular choice among gym buffs and elite athletes, so perhaps you should give it a try.

But what exactly is the keto diet and how does it work? Most importantly, is it right for you? Let’s find out!

What Is the Keto Diet?

This dietary plan has been around since the 1920s. It was originally intended to treat epilepsy in children. Researchers have found that when the brain doesn’t have access to glucose, it can use ketones for fuel. Elevated ketone levels may help reduce the frequency of epileptic seizures.

Sounds complicated? Here’s how it works.

After ingestion, carbs are converted to glucose and used for energy. This process is called gluconeogenesis. Your body needs glucose to function properly.

Keto diet
The ketogenic diet focuses on fats as the main source of daily calories intake.

The ketogenic diet limits carbs and encourages fat consumption, causing the liver to produce ketone bodies. The same happens during fasting. This puts your body into ketosis, a metabolic state that promotes fat loss.

While in this state, the body uses fat instead of carbs (glucose) for fuel. At the same time, your brain gets its energy from ketone bodies, which can improve mental health.

Under certain circumstances, your body can use protein for fuel. But we’ll discuss that later.

Studies Over the Years

Over the years, studies revealed that ketogenic diets may also help with fat loss. That’s how this eating pattern gained popularity among dieters and fitness enthusiasts alike.

Famous Golden Era bodybuilders Serge Nubret and Samir Bannout — the Lion of Lebanon, for example, followed the keto diet back in the 1980’s. Classic Physique superstar Breon Ansley goes on keto for three to four weeks before competing — and his hard work definitely pays off.

The keto diet basics are quite simple. Cut down on carbs, load up on fats, and eat protein in moderation. It’s no need to weigh your food, reduce portion sizes, or track calories.

What Happens to Your Body on the Keto Diet?

As we’ve stated above, the keto diet is low in carbs. Several versions exist, and each has different requirements regarding your carb intake. The amount of carbs you can eat also depends on your insulin sensitivity.

Weight loss on Keto
Keto diet leads to healthy weight loss when applied properly.

Some dieters can consume up to 100 grams of carbs and still remain in ketosis. Others cannot exceed 10-20 grams of carbs per day. In general, a daily intake of 30 to 50 grams of carbs will do the trick.

keto diet macros
The macro-nutrient distribution on a keto diet.

The typical macronutrient ratios are 5% to 10% carbs, 15% to 30% protein, and 60% to 75% percent fat, but these numbers can be adjusted according to your individual needs. If you’re sensitive to carbs, you can simply eat more fat and cut back on carbs.

Ketosis Definition

But what is ketosis, anyway?

Your body enters this metabolic state during times of fasting or when glucose is not readily available. The liver begins to produce 3-beta-hydroxybutyrate (3HB), acetoacetate (AcAc), and acetone, these are known as ketone bodies or ketones. These molecules are always present in the bloodstream, but in low levels.

Ketosis occurs when ketone levels increase. According to a study in the Journal of Cerebral Blood Flow & Metabolism, the human brain gets 25% of its energy from these compounds after only three days of starvation (carb restriction in this case).

Ketones molecular structure.

When you’re in the ketosis, your body switches from burning glucose to burning fat for energy. This leads to weight loss, reduced blood sugar, and improved glycemic control, among other health benefits.

Contrary to popular belief, ketosis and ketoacidosis are not one and the same. The latter is a life-threatening metabolic state associated with type I diabetes and alcohol abuse. It results from excessively high glucose and ketone levels in the bloodstream.

The transition to ketosis can take a toll on your body, causing a number of symptoms that last anywhere between three and 14 days. We’re talking about the so-called keto flu.

Keto Flu Symptoms at a Glance

Keto-adaptation doesn’t occur overnight. Your body needs about two weeks to fully adjust to using fat for energy instead of glucose. During this time, you may experience flu-like symptoms, such as:

  • Dizziness
  • Lightheadedness
  • Upset stomach
  • Lethargy
  • Fatigue
  • Drowsiness
  • Muscle cramps and soreness
  • General weakness
  • Migraines
  • Poor sleep
  • Irritability
  • Brain fog

Some dieters also report strong sugar cravings, stomach pain, poor mental focus, and nausea. You may notice that your workout performance decreases. Luckily, these symptoms will go away soon. In fact, there are a couple of things you can do to enter ketosis faster.

Not everyone will experience these issues. In general, they tend to be more common among those who are new to keto or rely heavily on carbs in their day-to-day lives. If you eat 300 grams of carbs a day, it’s normal to feel sick when you go low carb. By “low carb,” we mean 10 to 50 grams of carbs daily.

Keto Flu
The keto flu has relative symptoms like migraines, irritability, brain fog, and many more.

So, what does it take to get out of the keto flu and feel like yourself again?

Water is the Key

First of all, drink plenty of water as dehydration will worsen your symptoms. Electrolyte formulas can help too — just make sure they are sugar-free. Consider taking supplements that contain potassium, calcium, magnesium, phosphorus, and chloride. These minerals help balance your electrolyte levels and keep your body functioning optimally.

Hydration is key on a keto diet.

Proper hydration is paramount. Glycogen, the stored form of carbs in the liver and muscles, binds to water in your body. Cutting down on carbs depletes your glycogen stores, which leads to increased urination and sweating. This can result in water loss, muscle soreness, cramps, low energy, fatigue, and poor physical performance.

At the same time, it’s important to increase your fat intake. Your body can no longer rely on carbs for energy, so it needs an alternative source of fuel. Load up on fatty foods to boost your energy levels and curb sugar cravings. MCT oil, coconut oil, and exogenous ketones are particularly beneficial.

Signs and Symptoms That You’re in Ketosis

Now the big question… How can you tell if you’re in ketosis?

Well, forget about going on a date in the first two weeks after you start dieting. Be prepared to deal with the so-called “keto breath,” which can be a huge turnoff. The culprit is acetone, one of the ketone bodies in your breath and urine.

Bad breath on keto
Keto breath is the result of acetone, which are ketone bodies in your breath.

Another sign to watch out for is an increase in urine volume. As your glycogen levels decrease, you’ll start to pee more often.

Additionally, you’ll feel less hungry and experience fewer cravings for sugar. According to a 2014 research paper published in Obesity Reviews, ketogenic diets suppress appetite and increase satiety. Researchers attribute these findings to the fact that ketone bodies cause positive changes in the brain by altering the hormones that control hunger.

Remember the old saying It gets worse before it gets better? It applies to the keto diet too.

Increases in Energy

Once the keto flu is over, your energy will skyrocket. You’ll experience greater mental and physical energy, improved concentration, and increased alertness. Compared to carbs, ketones and fat are more efficient fuel sources — which explains the surge in energy and mental focus.

If you’re still not sure whether or not the diet is working, you have three options:

  • Blood ketone meters
  • Breath ketone analyzers
  • Urine ketone strips

These devices measure the ketone levels in your blood, breath, or urine. They’re available in most pharmacies and online and have a low price tag.

Urine ketone sticks are the most popular choice. All you have to do is to collect urine in a small jar, insert the absorptive end of the strip, and check it a few seconds later. Its color will change based on the ketone levels in your urine.

Keto Diet Food List: What to Eat, What to Avoid

The ketogenic diet seems bland at first glance. Nothing could be further from the truth. From butter and sour cream to meat, fish, eggs, and avocado, there are plenty of delicious foods you can enjoy while on this plan. You can even eat extra dark chocolate, nuts, seeds, and berries. Not to mention bacon!

Your daily meals should be high in fat and low in carbs, with moderate amounts of protein. Too much protein can kick you out of ketosis, so you’ll have to start all over. The next time you go shopping, take this keto diet food list with you:

Keto-Approved Foods

foods on keto
Keto approved foods include fatty cuts of animal protein sources.
  • Butter and ghee
  • Coconut oil
  • Olive oil
  • MCT oil
  • Avocado oil
  • Lard
  • Fatty cuts of meat
  • Organ meats
  • Game meat
  • Poultry (chicken, turkey, duck, goose, quail, etc.)
  • Fatty fish (tuna, salmon, mackerel, sardines, etc.)
  • Eggs
  • All leafy greens (kale, lettuce, fennel, arugula, spinach, collard greens, etc.)
  • Fresh/dried herbs and spices
  • Avocado
  • Berries in small amounts
  • Shirataki noodles
  • Konjac flour
  • Apple cider vinegar
  • Bone broth
  • Coffee and tea (no sugar added)
  • Nuts and seeds in small amounts
Leafy greens
Leafy greens are a great choice to bulk up meals without increasing your carb intake.

Keto Foods to Limit

Enjoy the following foods in moderation. Watch your portions and track the carbs ingested.

Berries are one of the foods you need to limit on a keto diet.
  • Fermented foods (coconut kefir, sauerkraut, pickles, etc.)
  • Berries
  • Leeks
  • Zucchini
  • Cucumbers
  • Cruciferous vegetables
  • Nuts and seeds
  • Beans and legumes
  • Beets
  • Carrots
  • Artichokes
  • Sweet potatoes and yams
  • Full-fat milk and cheese
Dairy products
Dairy derivatives can have many grams of carbs that may hinder your progress on keto.

Foods Banned on the Keto Diet

Pastries and bread
Pastries, grain flour products and cereals are banned on a keto diet.
  • Any product made with grain flour
  • Whole grains and breakfast cereals
  • Corn and its derivatives
  • Sugary foods
  • Pastries
  • Most fruits except for avocado and berries
  • Processed meats
  • Protein bars except for low-carb or zero-carb varieties
  • Soft drinks
  • Smoothies and fruit juices
  • Caffeine beverages
  • Alcohol
  • Sugar in all its forms (white sugar, coconut sugar, fructose, dextrose, glucose, etc.)
Caffeine beverages are a “NO” drinks on keto for hidden sugar content.

Processed meats, for example, may contain hidden carbs. The same goes for most diet foods, including those labeled “sugar-free.” Manufacturers often use dextrose, high fructose corn syrup, fruit juice concentrate, and other high-carb ingredients to enhance food flavor.

To stay on the safe side, choose minimally processed foods.

Keto Diet Basics: Try These Smart Food Swaps

The keto diet is anything but boring. Who knew that you can enjoy decadent treats like pizza, cloud bread, meat pie, or coconut porridge and still lose weight? The key is to swap ingredients.

Let’s take pancakes, for example. Mix coconut oil, psyllium husk powder, high-fat cottage cheese, and eggs to make the butter. Add stevia for extra sweetness. Top with heavy cream and fresh strawberries.

Any recipe can be made to be keto friendly, even pancakes!

Replace traditional bread with cloud bread. All you need is cream cheese, eggs, and a pinch of salt. Or you can simply swap bread for baked or grilled Portobello mushrooms.

If you’re craving pasta, use shirataki noodles or zucchini noodles in your favorite recipes. Add sour cream, ground meat, and mozzarella cheese or parmesan.

Cauliflower rice is an excellent substitute for regular rice. You can even use mashed cauliflower instead of mashed potatoes.

Cauliflower is a keto approved swap that can bulk up meals.

For desserts, replace sugar with stevia and grain flour with coconut, almond, or konjac flour. Swap milk chocolate for extra dark varieties or raw cocoa powder.

If you’re craving potato chips, enjoy a handful of zucchini chips, baked cheese chips, or pork rinds. Use lettuce leaves instead of tortillas and coconut oil instead of vegetable oil.

Does It Live Up to the Hype?

Now that you’re familiar with the keto diet basics, you may wonder if it’s worth the effort. Yes, it does. Hundreds of studies confirm it. This plan works because it balances the hormones that regulate appetite, increases the efficiency of fat oxidation, and keeps you energized due to its high fat content.

A 2013 clinical trial published in the British Journal of Nutrition compared the effects of a low-fat diet versus a very-low-carbohydrate ketogenic diet. The latter has been shown to produce greater weight loss in the long run.

fat loss
Fat loss on keto has a lower risk of metabolic syndrome compared to other diets.

Another study, which was featured in The Journal of Clinical Endocrinology & Metabolism in 2003, shows that very low-carb-carb diets, such as the keto diet, are more effective than calorie-restricted low-fat diets for short-term weight loss. Furthermore, ketogenic diets promote visceral fat loss, leading to a lower risk of metabolic syndrome, insulin resistance, and cardiovascular disease.

Keto Benefits

The benefits are even greater for those who work out regularly. According to a 2016 study, the keto diet results in higher rates of fat oxidation when combined with exercise. This means that you’ll burn more calories and fat in the gym once you’re in ketosis.

This dietary plan not only aids in weight loss but also supports overall health. Clinical evidence shows that ketogenic diets may improve cardiac risk factors and lower insulin levels in diabetics. At the same time, it may help increase good cholesterol and reduce triglyceride levels by up to 44%.

If your goal is to get leaner, use this diet along with a potent fat burner like Vintage Burn™. This will allow you to shed fat and preserve lean mass while giving your metabolism a boost.

What Are the Risks of the Keto Diet?

Despite its proven health benefits, the keto diet may not work for everyone. If your daily meals are high in carbs, you might find it difficult to change your eating patterns. Plus, this dietary plan isn’t the best choice for those looking to build mass and strength.

The so-called keto flu can be a major turnoff. Some dieters experience severe symptoms, from lethargy and fatigue to constant nausea and vomiting. Others show no symptoms at all.

If you’re having low energy, don’t give up yet. Try a pre-workout formula like Vintage Blast™ to stay hydrated and energized. Rich in electrolytes and micronutrients, this keto-friendly supplement is designed to boost mental focus, accelerate recovery, and increase hydration so you can achieve peak performance.


Another drawback of the keto diet is that it’s quite restrictive and requires planning. You have to do everything right. On the positive side, several versions of this plan exist — and some are more flexible than others.

The cyclical ketogenic diet, for example, alternates between low-carb, high-fat days and carb loading. It’s a favorite choice for most athletes and bodybuilders. With this approach, you can go low-carb for five consecutive days and load upon carbs over the next few two days. Carb loading help replenish your glycogen stores, increasing your energy and stamina.

With the keto diet basics in mind, it’s up to you to decide whether or not it’s worth a try. Another popular option is the Caveman Diet, which enjoys huge popularity among CrossFitters and top athletes. Unlike the ketogenic diet, it doesn’t require tracking your macros. Grass-fed meat, pastured eggs, nuts and seeds, fish, seafood, fruits, and vegetables are all allowed.

Have you ever tried the keto diet? Do you have any tips to get into ketosis faster? Share your experience below!

Disclaimer: None of the individuals and/or companies mentioned necessarily endorse Old School Labs or COSIDLA Inc. products or the contents of this article. Any programs provided for illustration purposes only. Always consult with your personal trainer, nutritionist and physician before changing or starting any new exercise, nutrition, or supplementation program.
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  • Not a fan of keto. When the body starts using fat for energy it puts into a survival type mode. Also going high fat seems like a good way to have a heart attack. Not a nutritionist or dr but just seems dangerous. The body needs protein carbs and fat. Eat smart and do the work

  • Very informative article – but I’m curious, why is it necessary to keep An eye on low carb, cruciferous veggies ?

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