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When Should You Try A Low Carb Diet?

by Laura Beth Schoenfeld, RD

Published on

low-carbohydrate diet, how low carb should I go
Diabetics can thrive on a low-carbohydrate diet. BananaStock/BananaStock/Thinkstock

Recently, I wrote an article about the potential pitfalls of following an excessively low carb diet, and the symptoms to watch out for to know if you’d benefit from adding carbs back into your diet. While I repeatedly pointed out that there are many people who thrive on a very low carb or ketogenic approach, there were commenters who staunchly disagreed with my recommendations.

While I stand by my original article (as well as Chris’s subsequent supporting articles here and here), I wanted to make sure that those who would benefit from a very low carbohydrate or ketogenic diet were aware of the positive impact this nutritional approach can have when implemented correctly.

Yes, you read that correctly: there are many people who can do incredibly well on a properly designed, nutritionally adequate ketogenic diet.

Some people find that they thrive on a very low carb or ketogenic diet. Could you be one of them?

In this article, I’ll describe seven different classes of people who could experience improved health and wellbeing by following a ketogenic diet, as well as briefly explain the precautions you’ll need to take if choosing to experiment with this therapeutic diet strategy.

Overweight and Obesity

One of the biggest draws of a low carbohydrate diet is that it can be a highly effective tool for rapid weight loss, especially in those who are significantly overweight and/or obese.

When compared to low fat diets, dozens of studies show that a very low carb approach can be help those who are overweight lose weight, maintain lean muscle mass, and improve many of the metabolic risk factors for diabetes and heart disease, including elevated triglycerides, low HDL, and chronically elevated blood sugar. There’s no denying that a low carb diet can be a highly effective obesity treatment.

Most people believe low carb diets cause weight loss so rapidly by lowering circulating insulin, but another reason why low carb dieting may promote weight loss is because these diets frequently lead to a spontaneous reduction in overall food intake. Combining that with low insulin and high glucagon levels is generally a recipe for immediate weight loss, though this is not always sustainable for a variety of reasons.

The longer a person stays on a low carb diet, the more they may start to find ways to make their diet more palatable, and thus increase their overall calorie intake. Also, as weight loss occurs, a person’s overall calorie expenditure will drop, meaning that the same amount of food that made them lose weight in the first place will eventually cause them to maintain their weight – the dreaded “plateau”.

If you’re eating more calories than you’re expending, even on a low carb diet, you won’t lose weight. If you’re using low carb as a weight loss diet, this doesn’t give you license to eat high fat foods in unlimited quantities. Eat good quality protein, plenty of non-starchy vegetables, and enough fat to meet your daily needs without going overboard and you may find that a nutrient-dense low carb diet is the perfect strategy for sustainable weight loss and reversal of metabolic syndrome.

And remember – obesity is a far different health situation than trying to “lose the last 10 pounds”, so many of the same weight loss principles that work well for people who are significantly overweight may not work so well for those trying to reach their ideal “look good naked” weight. Keep that in mind when considering how much weight you want to lose and whether or not it’s truly necessary for health purposes. Those who don’t really have much excess weight to lose may be more prone to the potential problems with a long term low-carb diet.

Blood Sugar Imbalances

Blood sugar control plays an important part in weight management as well as the prevention of chronic disease, including diabetes, heart disease, cancer, and possibly even Alzheimer’s disease, among others.

If your blood sugar is always elevated, you’re at an exponentially higher risk for dozens of diseases, and you’re more likely to die earlier from these diseases as well. So if you have consistently high blood sugar, you’ll likely find that reducing your carbohydrate intake significantly can bring that number down quickly, particularly if you’re relatively sedentary.

Low carb diets can also be helpful in reactive hypoglycemia, a condition where blood sugar drops too low following a meal, causing symptoms such as dizziness, anxiety, shakiness, hunger, and confusion. This issue can be made worse by caffeine and stress, and I find it more commonly in my clients with adrenal issues.

A common cause of this reaction is when a meal too high in easily absorbed carbohydrates is consumed, and blood sugar rises rapidly, leading to a release of insulin. The insulin causes a subsequent drop in blood sugar, and this drop can sometimes go too low or happen too quickly, leading to the hypoglycemic symptoms.

If you’re someone who eats a lot of sugar-laden foods, or generally is eating a high carb, low fat diet, you may be more prone to these blood sugar swings that can lead to hypoglycemia symptoms. In this case, a reduction in carbs and an increase in fat at meals will help keep your blood sugar levels steady, and get you off the blood sugar roller coaster. But if you’re already eating a very low carbohydrate diet, a bit of healthy carbs at each meal may actually help normalize your blood sugar too, so it’s important to consider your current dietary habits before dropping your carbs any lower.

And if you’re completely unsure where you stand on this issue, it might be worthwhile getting some help with your diet!

Neurological Disorders

One of the oldest uses of a ketogenic diet has been the treatment of seizure disorders  – even the Bible refers to fasting as a treatment for “fits”, and the ketogenic diet has been used by doctors as a treatment for epilepsy since the early 1900s.

Though the creation of anti-seizure medication significantly reduced the reliance on this treatment, there has been a surge in the demand for this therapeutic diet over the past 20 years. These days, there are even dietitians who specialize in the ketogenic diet who work with patients, mostly children, suffering from frequent seizures.

Other neurological conditions that have been shown to respond well to a ketogenic diet are Parkinson’s disease, Alzheimer’s disease, ALS, stroke, and dementia. (1, 2, 3, 4, 5, 6) In fact, Alzheimer’s disease is now being referred to as Type 3 Diabetes, highlighting the importance of blood sugar control in managing this often devastating condition. Ketogenic diets may also be therapeutic in the treatment of traumatic brain injury, a major cause of mortality and morbidity in young adults. (6a)

One of the most comprehensive books covering the role of a low carb and/or ketogenic diet in the treatment of neurological conditions is Grain Brain by Dr. David Perlmutter, a well known neurologist. Dr. Perlmutter has had a great deal of success using low carb, grain-free, and ketogenic diets in the treatment of thousands of patients with neurological disorders.

However, it’s important to remember that while these very low carb diets are helpful in treating these conditions, it’s unknown whether or not these restrictive diets would be necessary to prevent these conditions. Ultimately, I’d personally reserve the use of a ketogenic diet as a treatment for neurological disorders rather than a long term preventative diet.

Mood Disturbances

Similar to the neurological conditions already discussed, low carb and/or ketogenic diets may be helpful in reducing or eliminating symptoms of mood disorders like anxiety or depression. Some preliminary evidence suggests that these diets can have similar effects as antidepressant drugs. (7) Most of the research has been conducted in animals, but there have been studies showing benefits in improving aggression, fear behavior, and overall mood and quality of life. (8, 9, 10, 11)

On the contrary, one study demonstrated a decline in overall mood in subjects on a low carb diet, energy-restricted diet compared to a low fat diet, while another showed a decline in mood in female cyclists following a low carb compared to moderate and high carb diets. (12, 13) There hasn’t been a ton of research on this issue, so ultimately you’ll have to determine for yourself what the appropriate level of carb intake will be for your particular mood issues. I’ve seen plenty of clients (myself included) who find that their levels of anxiety skyrocket on an excessively low carb diet, so what works for one person (or a rat!) may not work for you.

Whether or not carbs are at play in your anxiety or depression, there’s a major role for a healthy diet and ancestrally appropriate lifestyle.

I do believe food is medicine when it comes to mood issues, and I’ve seen multiple clients get off their antidepressants after making targeted, individualized changes to their diets, even if they were already eating “Paleo”. And none of these improvements required strict carbohydrate restriction, so a moderate intake on a nutrient-dense diet may be enough to see positive changes.

Polycystic Ovarian Syndrome (PCOS)

PCOS is an incredibly common endocrine issue in young women, with a prevalence as high as 15%-20% of women. Typically, PCOS affects ovulation and menstrual function in women, and can also cause an androgen excess. These changes are the root cause of many of the most frustrating symptoms, including amenorrhea, acne, hirsutism (male-pattern body hair), weight gain, dandruff, thinning hair, and mood issues.

One of the primary dietary recommendations for women with PCOS is to limit refined carbohydrates and sugars, and to generally follow a lower carb diet. (14, 15) Reduced carbohydrate diets can help improve body composition, increase fat loss, repair insulin sensitivity, and promote menstrual regularity in these women (16, 17, 18)

One pilot study found that overweight women following a low-carbohydrate ketogenic diet lost weight, reduced their testosterone levels, and decreased their fasting insulin. (19) These women also experienced non-significant decreases in insulin, glucose, testosterone, HgbA1c, triglyceride, and perceived body hair. Two women even became pregnant during the study, when they had previously been experiencing infertility.

But before those of you with PCOS jump straight on a ketogenic diet, it’s crucial to note that there was no control group in this study. So it’s hard to know if the ketogenic diet was really necessary to get these results, or if a significant reduction in sugar, processed carbs, and grains might have been adequate, while still allowing these women to get a substantial amount of carbs from Paleo-friendly fruit and starchy vegetables.

You may find that the right diet for you allows for plenty of healthy variety, and that a reduced carbohydrate, whole foods diet is enough to get you on the right path towards healing from your PCOS.

Small Intestine Bacterial Overgrowth (SIBO) and Reflux (GERD)

SIBO and GERD seem to be increasingly common these days, likely stemming from our overuse of antibiotics, inadequate exposure to healthy bacteria, poor dietary choices, and high levels of stress. In my work with clients, I’ve also noticed an uncanny connection between SIBO or reflux and a history of binge eating or bulimia disorder, so I’d guess that overeating in general can put someone at higher risk for low stomach acid and an overgrowth of bacteria in their small intestine.

You can get great information about reflux from Chris’s free eBook on the topic. And if you’ve never heard of SIBO and you don’t know what the primary treatment for this condition is, I’d suggest listening to this podcast that Kelsey Marksteiner and I recorded for a great primer on the subject. But I’m sure some of you reading this either know what SIBO is, or actually have SIBO yourself. SIBO and reflux are often found simultaneously, so that’s why I’m lumping these two conditions together.

One of the primary dietary treatments for SIBO and reflux is the restriction of fermentable carbohydrates, often referred to as FODMAPs. But some practitioners even recommend using a completely low carbohdyrate or ketogenic diet, as some bacteria can feed off of low FODMAP carbs and starches. It may depend on the severity of your SIBO case, and some SIBO patients do just fine restricting FODMAPs and simple sugars. And if you’re eating too many high FODMAP veggies on a low-carb diet, you may actually make the problem worse!

Generally for reflux and/or SIBO, I tend to recommend a lower carbohydrate diet which restricts fermentable carbohydrates and sugar, but allows for a moderate amount of starches such as white rice or potatoes, which are often well tolerated. So while a strict low carb or ketogenic diet may be useful in dealing with these digestive disorders, I don’t think that it’s necessary to stay on these diets indefinitely to get the results you’re looking for.


At the risk of opening a giant can of worms, I’ll briefly mention that there are many scientists, doctors and clinicians who promote the use of a low carb ketogenic diet for cancer. The major argument is that unlike the majority of our body cells, cancer cells lack the ability to metabolize ketones, and require a significant amount of glucose to survive and replicate. Since a ketogenic diet can keep blood sugar low, the theory (in a nutshell) is that cancer cells won’t be able to survive and thus the cancer will not grow and metastasize. Some doctors have reported amazing results in the use of these diets in helping their patients go into remission.

There are a few studies that show potential benefits for some (but not all) cancer patients, especially brain cancer. (20, 21, 22, 23, 24) But another study showed that in 16 patients with advanced metastatic cancer, only 5 of the 16 patients recruited could even stick to the diet, and none showed any remission of the cancer, so it likely depends on the type and severity of the cancer whether or not a ketogenic diet will make any difference to the outcome. (25) And none of these studies show any data that suggests a ketogenic diet would be necessary or helpful to prevent cancer.

When it comes to dietary recommendations and carbohydrate restriction for cancer patients, I don’t know if there’s enough data on the subject to make a strong recommendation either way. Ultimately, we’ll always have some level of sugar circulating in our bloodstream, and while I agree that good blood sugar control is likely helpful in preventing cancer in the first place, I’m not entirely convinced that a ketogenic diet is the best diet in all cancer patients, especially for those who are in more advanced stages. And having had relatives die from advanced stage cancer, I can also understand the fear that would come from feeding a cachexic cancer patient a hypocaloric ketogenic diet if they’re already wasting away.

For now, I’ll “plead the fifth” on this topic, and wait and see if more studies come out in the future supporting this particular therapeutic use of the ketogenic diet.

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Important Considerations When Starting a Low Carb Diet

As you can see, a low carb diet can be a good choice for certain people, as long as they pay attention to several important factors that can ensure their nutritional status isn’t negatively impacted by this somewhat restrictive diet.

The biggest issue I see with many people who first switch to a low carb diet is that they’re unintentionally undereating, largely due to their discomfort with eating enough fat to make up for the carbs they’re not consuming. While this can be okay in the short term, especially for weight loss, over time this can lead to malnutrition and unhealthy stress on various organs, and may even cause weight gain as the body tries to conserve energy. If you’re on a low carb diet, make sure you’re eating enough to support your daily activity and to get a wide range of nutrients.

Also, even though some of your favorite foods might be low carb – like bacon, cheese, steak, and butter – make sure you’re still eating plenty of nonstarchy vegetables. These will help keep your gut bacteria healthy, as well as providing a variety of important minerals that can get deficient on a low carb diet. Potassium is a particular mineral that is prone to deficiency on a low carb diet, so eating a wide variety of vegetables and low carb plant foods at every meal (in addition to nutrient-dense animal foods) will help keep you nourished.

Avoid low carb products sold in the grocery store. These products often have artificial sweeteners and other additives that make them taste similar to their high carb counterparts, and sometimes can cause digestive distress in larger quantities. If you’re going to do a low carb diet, make sure you’re still eating real food and not buying a ton of low carb packaged food to replace the junk food you used to eat.

It’s important to keep an eye on your blood work as well, since not everyone experiences positive results on a low carb diet. Franziska Spritzler is a low carb dietitian who explained the adverse effects she experienced on a low carb ketogenic diet, with her LDL cholesterol and particle number shooting up to a potentially dangerous level. While this won’t happen to everyone, if it does happen to you it may be a sign that the diet isn’t a great choice for your long term health.

Finally, pay close attention to how you look, feel, and perform while on a low carb diet. While you’ll need to give it some time to truly determine if the diet can support your activity, energy, and daily lifestyle, it’s hard to know who will thrive and who will crash and burn on a long term low carb diet. If you’re experiencing negative health effects like excess weight gain, sluggishness, mood issues, or poor athletic performance after trying the diet for several weeks, it may be a sign that you’d do better on a more moderate carb approach. Don’t let someone else’s experience with the diet dictate how you should expect to feel. You’ll be your own judge when it comes to figuring out the most appropriate diet for you.

And if you need help figuring out how to optimize your carbohydrate intake, don’t hesitate to get in touch with me – I’ve worked with dozens of clients in this situation and can help you figure out if a low carb diet is right for you. You can sign up for a free 15 minute consult and we’ll discuss your nutrition and health concerns and determine if you’d benefit from professional and personalized guidance.

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Laura Beth Schoenfeld, RD
Laura Beth Schoenfeld, RD

Laura Schoenfeld, MPH, RD, is a licensed registered dietitian and women’s health expert trained in Functional Medical nutrition therapy. She assisted in the creation of educational materials for both the ADAPT practitioner and health coach training programs.

Her passion is empowering women to nourish their bodies, develop true strength, and ultimately use their improved health to pursue their purpose. Laura guides her clients in identifying and implementing diet and lifestyle changes that allow them to live a healthy, fit, symptom-free life without being consumed by thoughts of food and exercise. She draws from a variety of sources to form her philosophy on nutrition, including ancestral diets, principles of biochemistry, current research, and clinical experience. Her areas of expertise include women’s hormones and fertility, gut health, autoimmune disease, athletic performance, stress management, skin health, and weight loss. Recognizing that health goes far beyond just diet and exercise, Laura teaches her clients how to focus on and implement life-changing mental and spiritual health habits as well, including changing their thoughts and beliefs to ones that drive health-supporting decision-making around food, fitness, and life in general.

Her greatest mission is to help health-conscious women realize that, while their health is priceless, they are so much more than a body. When she’s not educating and serving her coaching clients and community, Laura loves traveling with her husband, Sundays with her church family, hikes with her dog, beach trips, live music, and strength training.

Professional website: lauraschoenfeldrd.com

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Join the conversation

  1. I was diagnosed with PCOS 24 years ago when I was 19. I have never had more than 2-3-4 periods per year and also have never had 3 periods in a row. Three months ago I started ketogenic diet. Not only did I kose weight but my blood sugar tests came back as in the normal range (I had had insulin resistance) and surprisingly I have had 3 periods in a row, each exactly 24 days apart! My body now has a rhythm. I cant believe it!

  2. A lot of diets programs often restrict your food alternatives however carb cycling does recommend some of general healthy eating guides as good as low carbs intake. The carb cycling meal plans diet compels the body to metabolize fat and protein to produce a matter as known as a ketone. So, the body burning fat for energy will generate Ketones.

  3. I must, with all due respect, humbly disagree with your statement, “The longer a person stays on a low carb diet, the more they may start to find ways to make their diet more palatable, and thus increase their overall calorie intake.” When I was on a very low carb diet (around 30 grams a day, which was strictly from veggies), and found myself needing a more “palatable” meal, I simply found recipes that used what I already ate. For example, instead of eating plain broccoli on my salad, I might make myself some broccoli soup using nuts and seeds and avocado as a base for it, along with some spices to enhance that dish. Dr. Furhman, of the “Eat to Live” protocol is right on the money when he says a “high nutritarian diet” is the way to go for fairly quick weight loss and sustainable weight loss.” (Dr. Furhman, 2016). I must agree with him since I adopted this protocol back in 2012 and was able to take some weight off and keep it off. Had I continued on the protocol (I had a death in the family and went off the protocol…when you’re grieving…you don’t care about diet or any other thing), I would be even less weight than I am now. The point I’m making is if a person is “more hungry” then the thing to do is to eat more veggies and more whole foods. At that time, I was strictly a vegan but now I do add some tuna fish to my salad as a means to get some more protein in, especially since I loathe beans and beans are a huge vegan staple for protein. Dieticians simply go by a standard way and think EVERY person should adopt a certain way. You’re right SOME people do very well on a low carb diet. Those of us with autoimmune conditions whereby our metabolisms are extremely slow and getting on a treadmill, and eating “well” all day long or within a strict caloric rage, doesn’t bode well with us. My endocrinologist started me out on 60 grms of carbs but I still couldn’t loose weight no matter how hard or how long I was in the gym and I could dance circles around some of those lightweights in the gym…but until and when I lowered my carbs to 30 grams; I knew I wasn’t going to lose. I think once I am down to the weight I need to be, I could probably add some more carbs and add more workout to balance that out but I may not. I’ll have to see. In the meantime, I’m going to follow my endocrinologists guidelines and trust that her medical degree has her knowing exactly what she’s talking about. Kindly, Mary

  4. I just wanted to share that a D2 obese client of mine has made significant progress over the past 6 months. As you noted, she had all the chronic disease markers including high cholesterol, triglycerides, low HDL, high LDL, low Vitamin D etc.
    Everything has significantly improved on a healthy low-carb diet including her A1c from 8.5 to 5.7 and all her cholesterol markers. She has also lost 43 pounds and has hit a plateau occasionally but exercise seems to help move the needle.

    While she still needs to lose more weight, seeing the results so far certainly has motivated her to continue.