Benefits and Risks of a Low-Carb Diet — and How Low Is Too Low?

September 26, 2017
Low-carb diets - Dr. Axe

Made famous by the Atkins diet and other similar weight-loss plans, low-carb diets are most well-known for shedding pounds fast.

But despite what might initially come to mind when you think about low-carb diets — loads of meat, cheese and butter on top of constant bread cravings, for example — we know now that a balanced low-carb diet (like the ketogenic diet) done right poses few, if any, major health risks and can be effective for far more than weight loss.


Should You Try a Low-Carb Diet?

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

How do low-carb diets work?

The benefits of low-carb diets mentioned above are 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, sweeteners of all kinds — and even nuts, seeds and vegetables.

Once glucose from carbohydrates is no longer available for energy due to following a low-carb diet, we begin to burn stored fat instead and experience weight loss fast. 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.

Glucose quickly runs out, and when our supply is low enough, the body turns to fat for fuel as a backup — luckily whether it’s coming from our diet or our own body fat.

A ketogenic diet — one form of a very low-carb diet — takes this process to the next level, strictly eliminating almost all sources of glucose in order to put the body into fat-burning mode quicker by focusing on fat-burning foods. Ketogenic diets have well-documented benefits, including helping to treat epilepsy, rapid weight loss and reduced diabetes risk. A traditional ketogenic diet is focused on eating about 75 percent fat, 5 percent carbohydrates and 20 percent protein. But most people don’t need to go this low-carb in order to experience great results.

Simply by focusing on eliminating major sources of sugar and carbohydrates — especially from grains and possibly legumes and dairy, too — while also increasing calories from healthy fats and quality proteins, most adults will see fast weight loss and improvements in overall health. 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.


8 Benefits of Low-Carb Diets

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 than the low-fat diets were, as demonstrated by 148 participants following both types of dietary plans over 12 months.

Why are low-carb diets 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 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-signalling mediators. As one might expect, the unhealthy diet high in sugar but low in healthy fats like omega-3 fatty acids was associated with lower cognitive scores and insulin resistance.

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 carb intake, thus there’s a decrease in perfusion of brain tissues and activity.

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 and at least equally effective at reducing weight and other factors.

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. Plus, you avoid the risks of low-fat diets.

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.

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 bodyweight of patients in the low-carb diet group was also observed, and this remained one year later.

 

Low-carb diet benefits - Dr. Axe

 

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. 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.

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 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. 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.”

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.

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.

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.

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.


Risks of Low-Carb Diets: How Low Is Too Low?

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.

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. Self-reports, along with data from certain trials, indicate that very low-carb diets or ketogenic diets might increase fatigue and irritability in some people — a side effect that has been nicknamed “the carb flu.” However, this is usually the case when cutting back carbs dramatically to just about 5 percent to 10 percent of total calories.

According to one 2007 study published in The Journal of the American Dietetic Association, blood ketone levels are directly related to feelings of fatigue and higher perceived effort during exercise in overweight adults adhering to low-carbohydrate diets. During the study, after overweight adults followed either a very low-carb ketogenic diet (5 percent of calories from carbs) or a moderate control diet (40 percent of calories from carbs), those with the most “ketones” detected in their blood due to very low intakes of glucose experienced the most dramatic mood changes, feelings of being tired and reductions in the desire to exercise.

On the other hand, data from other trials have shown the opposite: 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.

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 this type of side effect is something to monitor yourself for. If you’re feeling very sluggish, moody, or like you have “brain fog” and can’t think clearly while drastically reducing your carbs — 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.

Read Next: Mindful Eating — Maintain a Healthy Weight & Appetite


From the sound of it, you might think leaky gut only affects the digestive system, but in reality it can affect more. Because Leaky Gut is so common, and such an enigma, I’m offering a free webinar on all things leaky gut. Click here to learn more about the webinar.

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