What Is a Low-Carb Diet?

What Is a Low-Carb Diet?
 Made famous by the Atkins Diet and other similar weight-loss plans, low-carb diets are most well-known for shedding pounds fast. And despite what might initially come to mind when you think about low-carb diet plans — for example, eating loads of meat, cheese, oil and butter — research suggests that a balanced low-carb diet poses few health risks if done right.
In fact, certain low-carb diets, such as the ketogenic diet, have been shown to not only be very effective for weight loss, but also for improving other health markers such as blood sugar levels, as well as neurological health, hormonal balance and more.

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What Is a Low-Carb Diet?

A low-carb diet is a diet that limits carbohydrate foods — such as foods with added sugar, grains, starchy vegetables and fruit — and emphasizes foods high in protein and fat.
Low-carb diets are nothing new and have been used in the medical community for a variety of purposes for more than a century. Based on decades of research, low-carb diets have been linked to benefits including:

• fast weight loss
• reduced hunger
• better control over insulin and blood sugar
• enhanced cognitive performance
• lower risk for heart disease factors
• reduced risk for certain types of cancer

The benefits of low-carb diets are mostly due to a reduction, or in some cases almost an entire elimination, of glucose. Glucose, or other molecules that can turn into glucose once eaten, are found in all carbohydrate foods — whether grains, legumes, starchy vegetables, fruits and sweeteners of all kinds. To a lesser degree even nuts, seeds and vegetables contain glucose.
How do low-carb diets work? They’re effective because they cause glucose to quickly run out, and when your supply becomes low enough, your body turns to fat for fuel as a backup source — whether it’s fat coming from your diet, or your own stored body fat.
Our bodies normally run on glucose or sugar for energy, but we cannot make glucose ourselves and only store about 24 hours worth within our muscles and liver. Once glucose from carbohydrates is no longer available for energy due to following a low-carb diet, we begin to burn stored fat for fuel instead. This is why low-carb diets often lead to fast weight loss and other metabolic improvements within a relatively short period of time.

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The Difference Between Low-Carb Diets: High-Fat vs. High-Protein

People can mean different things when referring to low-carb diets, which creates some confusion about what a low-carb diet might actually look like. For example, which type of low-carb diet is more common and more beneficial, high-fat or high-protein?

High-Fat, Low-Carb Diets (aka the Ketogenic Diet):

A ketogenic diet — one form of a very low-carb diet — is a high-fat diet that strictly eliminates almost all sources of glucose in order to put the body into “fat-burning mode,” also called nutritional ketosis. The ketogenic diet goes by several different names, including the “no-carb diet” or “very low carbohydrate ketogenic diet”(LCKD or VLCKD for short).
Ketogenic diets have been used by doctors to treat patients with epilepsy and metabolic conditions since the 1920s! They have well-documented benefits, including helping to treat epilepsy, promoting rapid weight loss and reducing diabetes risk. Not only have studies over the past century shown that the keto diet can reduce the amount of seizures patients suffer from, but it can also have positive effects on body fat, blood sugar, cholesterol levels, hunger levels and neurological health. (1)

• When you’re following a traditional ketogenic diet, you consume about about 75 percent of your daily calories from healthy fats, just about 5 percent from carbohydrates, and about 20 percent from protein.
• Ketogenic diets limit daily net carb intake to just 20–30 grams (net carbs are the amount of carb leftover when fiber is subtracted from total carbs).
• While the keto diet is a great fit for the right type of person, many people will still experience great results when eating a modified keto diet that is a bit higher in carbs, or “keto-cycling” or “carb-cycling” in which they boost carb intake on certain days of the week.
• Compared to high-protein diets, the ketogenic diet is considered “moderate protein.” It’s important not to over-consume protein on the keto diet because this can interfere with your ability to produce ketone bodies for energy and to enter nutritional ketosis.

You might have concern over how restrictive a ketogenic diet will be, and maybe you’re concerned about side effects or “carb withdrawal.” Initially, keto diets can cause some side effects that typically last 1–2 weeks.
However, data from certain clinical trials has shown that low-carb diets, even very low-carb ketogenic diets, can actually help improve mood and reduce fatigue and hunger. A 2007 study conducted by the Department of Psychiatry and Behavioral Sciences at Duke University Medical Center found that participants experienced significant improvements in a broad range of negative symptoms when following a very low-carb diet, even more so than participants following a low-fat diet. Those on the very low-carb reported less fatigue, cognitive symptoms, physical effects of hunger, insomnia and stomach problems than the low-fat diet group. (4)

High-Protein, Low-Carb Diets:

Generally speaking, people who are not intentionally controlling their protein take usually get about 15–25 percent of their daily calories from protein foods.
If you choose to follow a high-protein diet, your diet will be roughly distributed as 30 to 35 percent protein, 20 percent or less carbohydrates, and about 45 to 50 percent fat. With every meal you’ll want to incorporate 1–2 palm-sized portions of protein, such as fish or meat. (3)
The main difference between high-fat and high-protein diets is the amount of protein — in the form of meat, fish, eggs, etc. — that someone is eating. Higher-fat diets like the keto diet call for more healthy fats in the form of butter, oil and fattier cuts of meat, while higher-protein diets still include fats, but less.

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What Can You Eat On a Low-Carb Diet? 

How many carbs should you eat in a day on a low-carb diet?
Depending on who you ask, a low-carbohydrate diet can include any diet that involves getting less than 30 to 40 percent of daily calories/energy from carbohydrates.
Forty percent of your diet consisting of carbs is still a relatively high amount, so if you’re aiming to eat low-carb, you’ll probably want to consume a good deal less than this. On the other hand, low-fat diets are those that involve getting 25 to 30 percent or less of daily calories/energy from fat.

• Each person is different, but generally reducing carbohydrates to about 30 percent of your overall diet, while increasing fat to 40 percent and protein to 30 percent, is a great target to aim for.
• From there, you might choose to further tweak your macronutrient intake (“macronutrients” are fats, carbs and protein) to reach certain goals, for example, entering ketosis via a ketogenic diet.
• So how many carbs are included in a low carb diet?  If you eat 2,000 to 2,500 calories per day, getting 30 percent of your daily calories from carbs would equate to about 150 grams to 187 grams of carbs per day (each gram of carbs contains roughly 4 calories).
• You can consider this amount to be relatively low-carb, although it’s still a much higher carb intake then you’d eat on a diet like the ketogenic diet.

The best way to start eating a lower-carb diet is to simply focus on eliminating major sources of added sugar and carbohydrates — especially from sugar snacks, sweetened drinks, grains and possibly legumes and dairy, too. At the same time, work on increasing calories from healthy fats and quality proteins. By following these guidelines, most adults will see fast weight loss and improvements in overall health.
Keep in mind that everyone reacts differently to various dietary plans, and there isn’t necessarily a one-size-fits-all approach to low-carb dieting that is going to work best for everyone. Factors like someone’s age, gender, level of activity, bodyweight and genetic disposition all affect how that person feels when following a low-carb diet.
Therefore, it’s important to practice self-awareness if you plan to reduce your carb intake in order to arrive at the level of carbs in your diet that works best for you personally. This might take some trial and error initially, and it’s usually best to reduce carbs gradually in order to prevent side effects like cravings or being tired.
What can you eat on a low-carb diet?

1. Healthy Fats

Most healthy fats contain zero net carbs, especially the kinds listed below, which also have other health advantages. (4) Fats should be included in high amounts with every meal throughout the day.

• Healthy fats include saturated fats, monounsaturated fats and certain types of polyunsaturated fats (PUFAs), especially omega-3 fatty acids. It’s best to include all types in your diet, with an emphasis on saturated fats, especially compared to PUFAs.
• MCT oil, cold-pressed coconut, palm fruit, olive oil, flaxseed, macadamia and avocado oil, butter and ghee, avocado, lard, chicken fat or duck fat are all good choices.

2. Quality Proteins

Animal proteins (meat, fish, etc.) have very little, if any, carbs. You can consume them in moderate amounts as needed to control hunger. Overall, choose organic, grass-fed and fattier cuts of meat rather than leaner ones. For example, chicken thighs and legs are preferable to chicken breasts because they contain much more fat.

• Grass-fed beef and other types of fatty cuts of meat, including lamb, goat, veal, venison and other game. Grass-fed, fatty meat is preferable because it’s higher in quality omega-3 fats.
• Organ meats including liver
• Poultry, including turkey, chicken, quail, pheasant, hen, goose, duck
• Cage-free eggs and egg yolks
• Fish, including tuna, trout, anchovies, bass, flounder, mackerel, salmon, sardines, etc.

3. Non-Starchy Vegetables

• All leafy greens, including dandelion or beet greens, collards, mustard, turnip, arugula, chicory, endive, escarole, fennel, radicchio, romaine, sorrel, spinach, kale, chard, etc.
• Cruciferous veggies like broccoli, cabbage, Brussels sprouts and cauliflower
• Celery, cucumber, zucchini, chives and leeks
• Fresh herbs
• Veggies that are slightly higher in carbs (but still low all things considered) include asparagus, mushrooms, bamboo shoots, bean sprouts, bell pepper, sugar snap peas, water chestnuts, radishes, jicama, green beans, wax beans, tomatoes
• Avocado (technically a fruit)

4. Full-Fat Dairy

Dairy products should be limited to only “now and then” due to containing natural sugars. Higher fat, hard cheeses have the least carbs, while low-fat milk and soft cheeses have much more.

• Full-fat cow’s and goat milk (ideally organic and raw) and full-fat cheeses.

5. Snacks

• Bone broth (homemade or protein powder)
• Beef or turkey jerky
• Hard-boiled eggs
• Extra veggies (raw or cooked) with homemade dressing
• 1/2 avocado with sliced lox (salmon)
• Minced meat wrapped in lettuce

6. Condiments

• Spices and herbs, hot sauce, apple cider vinegar, unsweetened mustards, cocoa, powder, vanilla extract, stevia

7. Drinks

• Water, unsweetened coffee (black) and tea, fresh made vegetable juice, and bone broth

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Foods to Eat in Limited Amounts

You’ll want to limit foods including medium-starchy veggies that contain more carbs (like sweet peas, artichokes, okra, carrots, beets and parsnips, yams and potatoes), legumes, beans, fruit and dairy products like yogurt/kefir.
The amount you have of these will depend on how low-carb of a diet you’re following. As a general rule, have no more than 1/2 cup serving cooked per day.

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What Should You Not Eat on a Low-Carb Diet?

1. Any Type of Sugar

• White, brown, cane, raw and confectioner’s sugar
• Syrups like maple, carob, corn, caramel and fruit
• Honey and agave
• Any food made with ingredients such as fructose, glucose, maltose, dextrose and lactose

2. Any and All Grains

One slice of bread, or small serving of grains, can have anywhere from 10–30 net grams of carbs! Cereals and cooked grains typically have 15–35 grams per 1/4 cup uncooked, depending on the kind.

• Wheat, oats, all rice (white, brown, jasmine), quinoa, couscous, pilaf, etc.
• Corn and all products containing corn, including popcorn, tortillas, grits, polenta and corn meal
• All types of products made with flour, including bread, bagels, rolls, muffins, pasta, etc.

3. Nearly All Processed Foods

• Crackers, chips, pretzels, etc.
• All types of candy
• All desserts like cookies, cakes, pies, ice cream
• Pancakes, waffles and other baked breakfast items
• Oatmeal and cereals
• Snack carbs, granola bars, most protein bars or meal replacements, etc.
• Canned soups, boxed foods, any prepackaged meal
• Foods containing artificial ingredients like artificial sweeteners (sucralose, aspartame, etc.), dyes and flavors

4. Sweetened and Caloric Beverages

• Soda
• Alcohol (beer, wine, liquor, etc.)
• Sweetened teas or coffee drinks
• Milk and dairy replacements (cow’s milk, soy, almond, coconut, Lactaid®, cream, half and half, etc.)
• Fruit juices

Can you eat fruit on a low-carb diet? If so, which fruit has the least carbs? Berries, including blueberries, strawberries, blackberries, raspberries, are the best choice because they are nutrient-dense and low in carbs. Stick to about 1/4 to 1/2 cup per day.

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8 Benefits of a Low-Carb Diet

1. Fast Weight Loss

When it comes to losing weight, calorie counting is crazy, but shifting your attention to the types of foods you eat and focusing on mindful eating can make all the difference. Low-carb diets have a reputation for producing fast weight loss without feeling hungry or needing to count calories. In fact, many people experience weight loss following a low-carb diet even if they’ve tried “everything else” and never got the results they were looking for.
A 2014 study conducted by the National Institutes of Health found that after comparing the two in overweight adults, low-carb diets were more effective for weight loss and cardiovascular risk factor reduction compared to low-fat diets, as demonstrated by 148 participants following both types of dietary plans over 12 months. (5)
Why are low-carb diets, especially the keto diet, so effective for shedding excess pounds, even in people who normally struggle to lose weight? When we eat foods with sugar and carbohydrates, the hormone insulin is released as a reaction in order to elevate blood glucose (sugar). Insulin is often called a “fat-storage hormone” because one of its jobs is to signal cells to store as much available energy as possible. This energy is initially stored as glycogen from the glucose found in carbohydrates, since glycogen is our “primary” energy.
By eliminating carbohydrates from the diet and keeping the body’s glycogen stores low or almost empty, we can prevent insulin from being released and storing fat. Less insulin circulating around our bloodstream means that the body is forced to use up all of its glycogen stores, then reach into fat stores tucked away in our adipose tissue (body fat) for ongoing fuel.

2. Better Cognitive Function

Fat and carbohydrates usually have an inverse relationship in someone’s diet. Most people keep protein intake somewhat steady, but normally the more carbs and sugar people eat, the less healthy fats they consume. This is problematic because we need healthy fats for proper brain function, mood control and hormone regulation. While initially a sugary or high-carb meal might make you feel awake and alert, quickly after you’ll likely come crashing down and might feel tired, grumpy and irritable.
Sugar is addictive and has dramatic effects on the brain, especially when it comes to increasing cravings, anxiety and fatigue. On the other hand, certain kinds of healthy fats, including cholesterol, act like antioxidants and precursors to some important brain-supporting molecules and neurotransmitters that control learning, memory, mood and energy. Your brain is largely made up of fatty acids and requires a steady stream of fats from your diet in order to perform optimally.
Recently, a 2012 report published in The Journal of Physiology found evidence of strong metabolic consequences of a high-sugar diet coupled with a deficiency of omega-3 fatty acids on cognitive abilities. These effects were due to the association of consuming high amounts of glucose and insulin action, which control brain-signaling mediators. As one might expect, the unhealthy diet that was high in sugar but low in healthy fats like omega-3 fatty acids was associated with lower cognitive scores and insulin resistance. (6)
Research suggests the ketogenic diet is especially therapeutic when it comes to protecting cognitive health. Researchers believe that people with the highest insulin resistance might demonstrate a lower cerebral blood flow and, therefore, less brain plasticity. This is because insulin is a “vasodilator” and increases blood flow to promote glucose delivery to the muscles and organs, including the brain. This vasodilator function is stopped when someone develops insulin resistance over time from a high-sugar and high-carb intake, resulting in a decrease in perfusion of brain tissues and activity.
In certain studies, improvement have been observed in Alzheimer’s disease and dementia patients fed a ketogenic diet, marked by factors including improved mitochondrial function. (7) A European Journal of Clinical Nutrition study pointed to emerging data that suggested the therapeutic use of ketogenic diets for multiple neurological disorders beyond epilepsy and Alzheimer’s, including headaches, neurotrauma, Parkinson’s disease, sleep disorders, brain cancer, autism and multiple sclerosis. (14)

3. Reduced Risk of Metabolic Syndrome and Heart Disease 

A 2012 study published in The American Journal of Epidemiology found that low-carbohydrate diets are more effective at reducing certain metabolic and heart disease risk factors than low-fat diets are, plus at least equally effective at reducing weight and other factors. (8)
The study investigated the effects of low-carbohydrate diets (≤45 percent of energy from carbohydrates) versus low-fat diets (≤30 percent of energy from fat) on metabolic risk factors by conducting a meta-analysis of randomized controlled trials. Twenty-three trials from multiple countries with a total of 2,788 participants were included in the analyses.
The results showed that both low-carbohydrate and low-fat diets lowered weight and improved metabolic risk factors. But compared with participants on low-fat diets, people on low-carbohydrate diets experienced a significantly greater increase in “good” high-density lipoprotein cholesterol and a greater decrease in triglycerides.
They also experienced a lower reduction in total cholesterol and low-density lipoprotein cholesterol than the low-fat diet group. However, keep in mind that higher cholesterol levels have not been proven to contribute to heart disease!
These findings were true despite that reductions in body weight, waist circumference and other metabolic risk factors were not significantly different between the two diet groups. These findings suggest that satisfying lower-carb diets, which are higher in fat, can help beat heart disease factors just as well as diets that are harder to stick with and prone to leaving people hungry.

4. Lower Risk for Type-2 Diabetes

Researchers point out that despite the growing rates of type 1 and 2 diabetes and the accelerating cost of the resources needed to monitor and treat diabetic patients, the medical community generally hasn’t been successful at reducing either the number of people affected or the severity of the complications. While prescriptions for diabetes medications continue to climb, there’s a simple, effective, low-cost strategy that is proven to work with diabetes: Reduce the amount of sugar and starch in the diet.
Researchers from the Division of Endocrinology, Diabetes and Hypertension at SUNY University of Brooklyn point out that a high-carbohydrate diet raises postprandial plasma glucose and insulin secretion, thereby increasing risk of diabetes, heart disease, hypertension, dyslipidemia and obesity. (9)
Many studies have shown that a low-carb diet is a natural diabetes treatment and effective tool in the prevention of patients with type 2 diabetes. It can also help lower risks for diabetes complications and related risk factors like obesity or heart disease.
A growing body of evidence shows that although a diet high in “healthy carbs” like whole grains is still recommended to many sick patients, low-carbohydrate diets are comparable if not better than traditional low-fat/high-carbohydrate diets for weight reduction, improvement in the dyslipidemia of diabetes and metabolic syndrome as well as control of blood pressure, postprandial glycemia and insulin secretion.
In a 2005 study published in The Upsala Journal of Medical Science, for two groups of obese patients with type 2 diabetes, the effects of two different diet compositions were tested with regard to glycemic control and body weight. A group of 16 obese patients with type 2 diabetes was put on a low-carb diet (1,800 calories for men and 1,600 calories for women) that consisted of 20 percent carbohydrates, 30 percent protein and 50 percent fat.
Fifteen obese diabetes patients were put on a high-carbohydrate diet to serve as the control group. Their diet consisting of the same calories for men and women included approximately 60 percent carbohydrates, 15 percent protein and 25 percent fat. Positive effects on the glucose levels were seen very quickly in the group following the low-carb plan. After six months, a marked reduction in body weight of patients in the low-carb diet group was also observed, and this remained one year later. (10)

5. Help Fighting Cancer

Research shows that a diet high in refined carbohydrates and sugar contributes to free radical damage and actually feeds cancer cells, possibly helping them proliferate faster. Because low-carb diets dramatically cut down sugar and lower intake of grains and processed foods, they might act like a natural cancer treatment, causing immunity to improve as oxidative stress goes down.
Studies indicate that carbohydrate intake influences prostate cancer biology, as demonstrated through mice that have been fed a no-carbohydrate ketogenic diet (NCKD) experiencing significantly smaller tumors and longer survival times than mice fed a Western diet. (7) The mice fed the equivalent of the standard human Western diet had higher serum insulin, which was associated with significantly higher blood glucose and tumor tissue growth. (11)
In the process of cutting off the supply of energy to cancers, healthy cells are luckily preserved since they’re able to use fat for energy. Cancer cells, on the other hand, thrive off of glucose and cannot metabolically shift to use fat.

6. Fewer Cravings and Not Going Hungry!

One of the biggest benefits of a low-carb diet or the keto diet is that eating more healthy fats and proteins in place of sugar and carbohydrates is super satisfying, since it effectively helps turn off ghrelin, the “hungry hormone.”
According to studies, insulin negatively regulates ghrelin, and high-density lipoprotein may be a carrier particle for increasing circulating ghrelin. (12) In other words, carbs spike insulin quickly, which leads to cravings for more food later on as blood sugar drops and ghrelin increases. Fats and proteins, on the other hand, are known for switching on the body’s satiety hormones and allowing you to go longer comfortably between meals without needing to snack.
According to a report published in The Journal of International Studies of Obesity:

Leptin and ghrelin are two hormones that have been recognized to have a major influence on energy balance. Leptin is a mediator of long-term regulation of energy balance, suppressing food intake and thereby inducing weight loss. Ghrelin on the other hand is a fast-acting hormone, seemingly playing a role in meal initiation. As a growing number of people suffer from obesity, understanding the mechanisms by which various hormones and neurotransmitters have influence on energy balance has been a subject of intensive research. It is now established that obese patients are leptin-resistant. (13)

To get off the roller-coaster of insulin highs and lows, you need to gain control over your primary appetite hormones. The easier way to do this is to keep appetite-boosting sugar low and include quality proteins and fats with every meal, especially in the morning with breakfast, which sets the tone for the entire day.
Ketones that are created by the body during the ketogenic diet have also been shown to help curb hunger and to make intermittent fasting easier. In studies conducted on average weight adults, consumption of ketone supplements has been shown to lead to suppression of ghrelin, reduced hunger and less desire to eat. (14)

7. Better Digestion

Less sugar means better digestive function for most people, since sugar feeds “bad bacteria” that can thrive in the gut. The result of a diet too high in sugar and carbs can mean the development of candida virus, IBS and worsened symptoms of leaky gut syndrome. Plenty of vegetables, quality proteins and healthy fats, on the other hand, can act like fat-burning foods that also help nourish the digestive tract and reduce bacterial growth.
Research from a 2008 study published in the Journal of the American Gastroenterological Association showed that patients with irritable bowel syndrome (IBS) report symptom improvements after initiating a very low-carbohydrate diet (VLCD). When participants with moderate to severe IBS were provided a two-week standard diet, then four weeks of a VLCD (20 grams of carbohydrates a day), the majority reported improvements in abdominal pain, stool habits and quality of life. (15)

8. Better Hormone Regulation

You’ve already learned about the positive effects that a low-carb diet can have on insulin and appetite hormones, but going low-carb appears to also help balance neurotransmitter function in some people and thus improve mood.
When researchers from the Discipline of Psychiatry and School of Medicine at the University of Adelaide compared the hormonal and psychological effects of a low-protein, high-carbohydrate (LPHC) diet and a high-protein, low-carbohydrate (HPLC) diet in women with a hormonal disorder called polycystic ovary syndrome (PCOS) over the course of 16 weeks, they found a significant reduction in depression and improvement in self-esteem in those on the low-carb diet. (16)
All participants attended a weekly exercise, group support and educational program and completed the Hospital Anxiety and Depression Scale at the beginning and end of the study. The HPLC diet appeared to help balance hormones naturally and was associated with significant reductions in various depressive symptoms, enhanced feelings of well-being and higher likelihood of having better compliance with long-term treatment of obesity.

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Precautions When Starting a Low-Carb Diet

Overall, there seems to be a lot of variability when it comes to how low-carb dieting and changes in moods and energy levels — with some people feeling great and others struggling a bit initially. This is why it’s important to pay attention to how you feel as you change your diet, and make adjustments as necessary.
Self-reports, along with data from certain trials, indicate that very low-carb diets or ketogenic diets might increase symptoms like fatigue, constipation, brain-fog and irritability in some people — side effects that have been nicknamed “the carb flu” or “keto flu.” However, this is usually the case when cutting back carbs dramatically to just about 5 percent to 10 percent of total calories. These side effects usually clear up within 1–2 weeks of changing your diet, after your body adjusts.
Obviously, reductions in the desire to be physical active, experiencing brain fog and being cranky are pretty counterproductive for people looking to feel healthier and lose weight, so these effects are something to monitor yourself for. If you’re feeling very sluggish, moody, or like you have “brain fog” and can’t think clearly while after drastically reducing your carbs over the course of several weeks — especially if you changed your diet rapidly and reduced carbs to very low ketogenic levels — try reintroducing some carbs several days a week until you feel better. Experiencing the benefits of low-carb diets can take some trial and error, plus some patience.

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Final Thoughts on Low-Carb Diets:

• A low-carb diet is a diet that limits carbohydrates — such as from foods with added sugar, grains, starchy vegetables and fruit — and emphasizes foods high in protein and fat.
• Benefits of low-carb diets include: help with weight loss, reduced hunger, better control over insulin and blood sugar, enhanced cognitive performance, lower risk for heart disease factors, improved neurological health, and reduced risk for certain types of cancer.
• Low-carb diets tend to be either very high in fat or high in protein. A very high-fat, low-carb diet is called the ketogenic diet. This diet causes the body to create ketones and burn fat for fuel, which has many benefits.
• On most low-carb diets, you get about 30 percent or less of daily calories from carbs. Keto diets involve getting 75 percent or more of calories from fat, while high-protein diets usually entail getting 30 percent or more of calories from protein.
• Low-carb diets or ketogenic diets might increase symptoms like fatigue, constipation, brain fog and irritability in some people. These side effects usually clear up within 1–2 weeks, although some people will ultimately feel better eating a more moderate-carb diet.