Medically reviewed by Kelly Kennedy, RD
When I stepped on the scale, and the needle raced past 200, I knew I had a problem. I was always thin and active as a young man. In college, I was 5 feet 10 inches tall and weighed 154 pounds (lbs). Now, closing in on a half-century of life, over two decades of desk jobs had since passed. The birth of my son made sleeping more of a hobby than a necessity. The long hours and the stress of owning my own business caused me to make my food choices based on speed and price rather than nutrition and fuel. My body was running on Coca-Cola, bagels, and pizza. So I shouldn’t have been surprised when the needle on the scale settled at 208 pounds, but I was still shocked. You never think you are going to become a statistic. But as more and more Americans become overweight, I was part of a not-so-exclusive club.
When I started looking into ways to lose weight, it was hard to avoid the ketogenic diet. In my mind, it was the latest in a long line of diets that have raced through popular culture in my lifetime: Atkins, South Beach, Zone, paleo. It seemed like there was a new magic solution every few years. The difference with keto was that although I was giving up a lot of things I really liked (pizza, pasta, soda), there were quite a few foods that were staples of the diet that I enjoy (meat, fish, spinach, broccoli). I wasn’t quite ready to make the commitment to such a strict diet, but I decided to take some baby steps.
After a day of feeling extremely depressed, I decided to try to make my worst trip to the scale the best thing that ever happened to me. It wasn’t too late to change. At least I hoped it wasn’t. Every two weeks, I replaced something awful in my diet with something a little bit better. First, day-long Coke drinking was replaced by a maximum of two small Gatorades per day. That dropped the number of calories I was drinking from 1,000 to 220 each day. Two weeks later, bagels were next to go, replaced by two simple scrambled eggs for breakfast. By making those two changes, I lost 15 lbs in less than a month. I wasn’t that far under 200 again, but it was a start. Increasingly restricting my simple carbohydrates was beginning to show immediate results.
If I was going to lose more weight, I needed to move around more. I started by walking to and from my son’s school to drop him off and pick him up each day. Each way was about 2 miles. Three weeks later, I was at about 185. Then I leveled off again.
To try to push through the plateau, I joined a boxing gym. I started with an amazing trainer named Joey Gamache. He is a former world champion, and he made me feel like a champion as well. Joey and I would try to train together four mornings per week — hitting the heavy bag and the speed bag, doing footwork drills. If you’re feeling as out of shape as I was then, you might think a boxing gym may not be a welcoming place for someone who is older, heavier, and a lot slower than they once were. It was the opposite. The people at Church Street Boxing Gym in New York City welcomed me with open arms.
Within three months, I knew everyone at the gym by their first name, something that never happened to me at health clubs. Even the professional fighters would give me a fist bump on the way to their morning workout. We weren’t competitors. We were all on the same team. The enemy was the couch and the TV. Every morning I was in the gym, I was with the extended family I never knew I was looking for. We were choosing life together.
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Stalled Weight Loss Led Me to Consider the Keto Diet
Four months into my new journey toward health, my weight had dropped from 208 to 168 lbs. In boxing terms, I had gone from a super heavyweight to a super middleweight. I was at my goal, and I felt great! When I got to 168 lbs, some of my friends at the gym thought that based on my body composition, I could easily make it down to 160 (middleweight). But once I got to 168, the weight was no longer coming off as quickly. By now I had eliminated most of the carbs in my diet, but I wasn’t following the ketogenic diet to the letter.
Nowadays, the keto diet is well known, arguably the biggest weight loss diet fad out there. But at the time, it was news to me. My thought process went something like this: “You mean there’s a diet that actually uses your body’s extra fat for energy? Where do I sign up?” Even though there were signs of life in my abs, going keto sounded like the perfect way to burn off the love handles and any other extra body fat that was clinging to my body for survival.
After doing some closer examination, I learned quite a bit about the diet. It turns out that the keto diet traces back to the 1920s, when doctors were trying to find a way to mimic the effects of fasting in children with epilepsy to lessen the frequency of their seizures, according to a report in Epilepsia.
A traditional keto diet menu consists of foods that are high in fat, extremely low in carbohydrates, with a moderate amount of protein to allow the body to repair itself. The diet fell into a more complementary role in the 1930s, when antiseizure medications were developed.
But when you look at how keto works, it’s not all so surprising that the high-fat diet has gained popularity as a quick way to lose weight. By inducing the natural metabolic state of ketosis, the body begins to use fat as a source of fuel instead of carbohydrates. When the body breaks down fat, it produces metabolites called ketones, which your body then uses for energy in place of carbohydrates.
When I saw the foods that were listed as being keto-friendly — chicken, eggs, and cheese — I thought this was something I could do.
There are several different types of ketogenic diets. I opted to try the standard keto diet, which includes getting 80 percent of calories from fat, 15 percent of calories from protein, and only 5 percent of calories from carbohydrates. That allowed me to consume only about 50 grams (g) of carbohydrates per day.
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3 Days Into the Keto Diet, I Felt Like I Needed a Flu Shot
The first two days on the diet, I felt a little more tired than usual, but it wasn’t anything I couldn’t handle. After working out hard for a few months, there would be days where I would feel more fatigued than others. I started to feel like that every day. I also felt very strange eating as much butter and oil as I was. Butter in particular is something we have been told for decades is really bad for you, and mentally, it’s hard to change those habits. But getting the fat to protein ratio right is critical. If you eat too much protein, it can actually knock you out of ketosis.
The rules of the keto diet are pretty strict, but they were easy to understand and follow. Pretty quickly the weight loss kick-started again. Within a week, I was down under 160 lbs for the first time, and 154 lbs (junior middleweight) was in sight. But the diet was proving to be pretty grueling. By the third day, I thought I was actually sick. I felt awful. I couldn’t think straight. I felt even more tired than I did when I was overweight. Traffic had come to a standstill in my digestive system. At times, the thought of having more coconut oil made me feel sick to my stomach. That’s when I learned about the keto flu.
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My Experience With the Keto Flu and Its Symptoms
The keto flu isn’t really a flu, though it feels like it. The symptoms that a person may feel when they begin the ketogenic diet mimic many of the symptoms of the common flu caused by the influenza virus. The fatigue is debilitating, as are the headaches. Nausea becomes a constant companion that won’t go away.
This Is Your Body on Ketosis: Constipation and Other Keto Flu Symptoms
As your body makes the transition from using carbohydrates for energy to burning fat for fuel, it goes through some adjustments that can lead to various new symptoms, which usually subside in a couple of weeks. Not everyone experiences keto flu symptoms on the diet. Unfortunately, I seemed to have collected most of the symptoms — headaches, mental fog, nausea, constipation. People experiencing keto flu often have difficulty sleeping as well. (I’m not a particularly great sleeper, so there wasn’t any way of knowing if this was an issue for me.)
Faced with all of these new ailments, I contacted Cynthia Sass, RD, who splits her time between Los Angeles and New York City.
Sass has worked with professional athletes at the highest level, including members of the New York Yankees and Brooklyn Nets. As many pro athletes have at least experimented with the ketogenic diet, I explained my symptoms to her and asked for her advice.
Mental Fog Within about three days on the diet, my brain felt slower, like it had just run a race and wanted to sit down. It felt as if I was living underwater all day. I just didn’t have the same ability to process things as quickly as I used to. I couldn’t concentrate on the simplest tasks. Focusing on tasks at work seemed like it required an exhausting amount of effort. For a writer, it’s an occupational hazard not to be able to organize your thoughts. Even passively reading something for fun felt like a chore.
“Despite accounting for only 2 percent of adult body weight, the human brain uses [up to] 25 percent of the body's total glucose at rest,” says Sass, referring to the body’s energy source created from carbohydrates. “These symptoms aren't uncommon as the brain is forced to adapt to a new fuel source. I don't think there is any way around the mental fog, as it just takes time for the brain to adjust.” But every day that it took to adjust, I was less and less productive at work. Articles that might take a day to write started to take three days. Professionally, I wasn’t sure how long I could continue to feel this way.
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Headaches I would get really bad headaches in the back of my head and neck. They felt similar to the headaches I would get when I first tried to kick my caffeine habit. At its worst, I would have to lie down in a dark room for an hour or so until they subsided. Ibuprofen (Advil, Motrin) provided no relief. “The headaches may be due to a combination of the brain switching fuels, in addition to dehydration and electrolyte imbalances,” Sass says. “Drinking more water and consuming more electrolytes could help alleviate the headaches.” A small, low-carb sports drink, which offers electrolytes, should do the trick.
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Occasional Nausea At first, I thought I felt nauseous because I wasn’t finding so much fat to be appetizing. To truly eat ketogenically, you have to limit yourself to about 50 g of carbohydrates per day. If you eat some fairly basic and very healthy foods like broccoli and bananas, you would be surprised how fast you can get to 50 g of carbs in a day. Three cups of broccoli with my meals for the day and a banana mixed with almond milk for a protein shake and I was pretty much at my daily limit of carbs. The rules are easy to follow on keto, but they are very unforgiving.
Adding the extra oils like olive oil and coconut oil intuitively didn’t feel right. In fact, it felt kind of gross. So I thought the nausea was a rebellion from the actual foods I had to eat. But it turns out, nausea is a fairly common side effect of the diet. “The nausea may also be due to dehydration and electrolyte imbalances,” Sass told me. “In addition, the enzymes that break down fat need to be ramped up to handle the higher fat load, and fats empty out of the stomach slower than carbs.” Sass advises considering plant-based fats that are healthier, like avocado and extra virgin olive oil, over animal-based fats, like butter, cream, and lard.
Constipation The keto diet definitely affected my body's ability to get rid of waste. I would often go an entire day without using the toilet, and when I did, it wasn’t very productive. “This is very common, since a limit of 5 percent of calories from carbs doesn't allow for much dietary fiber,” Sass said. “Eating fiber is like strength training for the muscles of the digestive tract. With a lower-fiber diet, the muscles aren't stimulated as much, so they contract less, which means waste moves through the GI tract more slowly. For this, it would be wiser to eat smaller meals and spend your carbs on high-fiber vegetables.”
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Weight Loss After 12 Days of Keto Dieting
On the keto diet, I made it down to my last goal weight of 154 lbs in just under two more weeks. While many may look at the results and say it was worth it, I didn’t feel that way at all. In boxing terms, I went from being a super heavyweight to a junior middleweight. And though I felt lighter on my feet, I also felt a lot weaker. At 168 lbs, I felt younger, energetic, as if I had a new life. People noticed the change and thought I had a new glow. On keto, I lost 14 additional pounds, but I felt like I was losing muscle. I felt weaker, older. It was as if I was willing my body to do something it didn’t want to do. I went from feeling like a superhero to feeling defeated.
So on the day I decided that being 154 lbs didn’t matter as much as feeling good, I cracked open a 32-ounce fruit punch Gatorade, the biggest bottle I could hold in one hand, and I drank it all in less than a minute. And it was delicious. It was like drinking a bottle of medicine. Within 30 minutes, I felt alive again. My energy level was back. It was as if someone turned on the headlights in my mind. The weight goals I had set were all arbitrary. The way I felt in this moment was real. I felt like myself again.
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Reflecting on the Aftermath of the Keto Diet
The more I researched, the more I realized I could have it both ways. I could maintain a healthy weight while still having enough carbs to help me feel like my brain was functioning and my body was strong and energetic. I slowly started to add some more healthy, complex carbs back to my diet. In the evenings, I added a second protein shake with a banana, some crushed ice, and almond milk. It was like having a guilt-free dessert. I also started experimenting with adding a small cooled-down baked potato with my lunch and dinner. By cooling it, the potato contained more resistant starch, which helped with digestion without sending my blood sugar as sky high. This time I skipped the butter and just added a little salt. Removing all of the calories from the butter allowed me to eat more food and even have a small Gatorade after my workout and still stay within my calorie targets of about 2,600 calories a day.
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Going on a more realistic diet that restricts my carbohydrates but doesn’t eliminate them entirely was the best dietary decision I made. I’m still able to eat portions of meat, chicken, and fish with vegetables that leave me feeling sated while keeping my calorie intake at the right level. For a snack, a few cubes of cheese or a handful of almonds is a perfect energy booster. Instead of thinking of it as food, I started thinking of it as fuel.
I also started time-restricting my meals. I eat my first meal of the day after I work out around 11 a.m., and I have my last food at around 8 p.m. The rest of the time, my body is fasting and continuing to use fat for fuel in addition to carbohydrates.
I’ve also listened to my body and added a lot more water to my diet. By staying hydrated, my body doesn’t hold on to water as much, and that helps keeps my weight down as well. Boxers know this well as they prepare to try to make weight for a fight. My new friends at the gym taught me well.
The biggest lesson I learned is that the keto diet may be right for some people, but it wasn’t right for me. The keto diet is great for people who like simple, straightforward choices on what to eat and do not experience any of the temporary flulike symptoms that come with following the diet to the letter. But by managing your carb intake more mindfully and incorporating a little more activity into your day, you can get to the same place. It’s not the destination; it’s the journey. And if you’re going to be on this journey for the rest of your life, you may as well enjoy each step.