Metabolic syndrome has become a significant problem, with the American Diabetes Association estimating the cost of diabetes and pre-diabetes in the United States alone to be $322 billion per year. Numerous clinical trials have demonstrated the efficacy of low-carbohydrate diets in reversing metabolic syndrome and its associated disorders.
This study was designed to examine how voluntary adherents to a low-carbohydrate diet rate its effectiveness and sustainability using an online survey.
The 57-question survey was administered online and shared internationally via social media and ‘low-carb’ communities. Where appropriate, chi-squared tests and paired
There were 1580 respondents. The majority of respondents had consumed less than 100 g of carbohydrates per day for over a year, typically for reasons of weight loss or disease management. There was a reported decrease in waist circumference and weight with a simultaneous decrease in hunger and increase in energy level. Of those who provided laboratory values, the majority saw improvements in their HbA1c, blood glucose measurements, and lipid panel results. There was a reduction in usage of various medications, and 25% reported medication cost savings, with average monthly savings of $288 for those respondents. In particular, the usage of pain relievers and anti-inflammatories dropped with a simultaneous decreased rating of pain and increase in mobility.
We conclude that low-carbohydrate diets are a sustainable method of metabolic syndrome reversal in a community setting.
The prevalence of obesity and diabetes in the United States and the world has increased dramatically over the last 40 years with no sign of correction. These diseases remain undefeated despite billions of dollars in research and health care costs.
At West Virginia University School of Medicine, where Dr Cucuzzella is a practising family physician and professor, outpatient and inpatient clinics are overwhelmed every day with cases of diabetes and metabolic syndrome. As of 2016, 37.7% of adults in West Virginia are obese. By best estimates, 15% have type 2 diabetes (T2D), and perhaps more than 50% have pre-diabetes.
This report describes a simple approach to reversing T2D and pre-diabetes (remission is defined as normoglycaemia for 1 year without active pharmacotherapy, with the disease ‘cured’ after 5 years)
Metabolic syndrome, or ‘Syndrome X’, was first identified by endocrinologist Gerald Reaven in the 1980s, and the root cause of this condition is described as ‘insulin resistance’.
The prospect of reversing progressive T2D is somewhat new to both the public and health care practitioners. Many assume the diagnosis is a purely progressive disease,
In current treatment approaches, pharmacotherapy typically is the focal point and carbohydrate restriction is de-emphasised. For instance, a recent Kaiser Permanente study involving 120 000 patients concluded that prolonged T2D remission in community settings without bariatric surgery is very rare; it occurred in only 0.007% of the study population. During the 7-year study, more study participants (1.7%) died than the percentage who experienced any level of remission, and diabetes-associated medication use, health care costs and complications increased.
The first well-recorded version of a low-carbohydrate diet was described in 1863 by the Englishman William Banting, who restricted starchy and sugary foods to overcome obesity on the advice of his physician.
The definition of a low-carbohydrate diet varies in the literature, but most in the field agree that anything over 130 g – 150 g per day is not low carbohydrate.
Numerous randomised, controlled trials have shown that well-formulated low-carbohydrate dietary patterns are highly effective for treating obesity and improving a spectrum of risk factors typical of patients with metabolic syndrome and diabetes who previously ate a traditional diet.
In a critical review of the literature, Feinman et al. present 12 points of evidence (summarised below) to support the low-carbohydrate diet as the best first-line strategy for treating T2D and the most effective adjunct to pharmacology in type 1 diabetes (T1D)
Dietary carbohydrate restriction has the greatest effect on decreasing abnormally high blood glucose levels, the most salient feature of diabetes.
Increased caloric intake, the driver of the obesity and T2D epidemics, has been due almost entirely to increased carbohydrate consumption.
Weight loss is not required to reap the benefits of a low-carbohydrate diet, which include reversal of T2D.
For weight loss, no other dietary intervention has proven to be better than carbohydrate restriction.
For people with T2D, the low-carbohydrate diet is as effective as other dietary interventions and often significantly better.
Replacement of carbohydrate with protein generally improves glycaemic control.
Total fat and saturated fat intake do not correlate with risk of cardiovascular disease.
Plasma-saturated fatty acid levels are affected more by eating carbohydrates than eating fats.
The best predictor of microvascular, and to a lesser extent macrovascular, complications in patients with T2D is glycaemic control (as measured by HbA1c).
Dietary carbohydrate restriction is the most effective method (other than starvation) for reducing serum TG and increasing high-density lipoproteins.
Low-carbohydrate diets reduce and frequently eliminate medications for T2D patients and usually result in lower insulin doses for patients with T1D.
Intensive glucose lowering by carbohydrate restriction has none of the side effects associated with intensive pharmacologic therapies.
Despite a growing body of evidence for low-carbohydrate diets’ superior results in the management of obesity, cardiovascular disease risk, metabolic syndrome and T2D, objections by the medical and public health communities persist.
Although a reduced-carbohydrate approach may theoretically improve health, if it is too difficult to follow long term or if it brings with it unwanted effects, the idea that people should reduce their carbohydrates is at best irrelevant. Our hypothesis is that if one adheres to a well-formulated low-carbohydrate diet, the success and health benefits can be maintained over years and even for a lifetime. To probe the real-life utility of such an approach, previous examinations of people following some kind of carbohydrate restriction have been conducted. For example, Tim Noakes, a South African physician and low-carbohydrate diet researcher, published an analysis of more than 100 communications he had received from people following some kind of carbohydrate restriction. The participants reported reduced weight, hunger, irritable bowel syndrome symptoms, hypertension and medication needs, as well as improved glycaemic control and exercise capacity.
The purpose of this research was to gain a detailed, updated understanding of adults who were already voluntarily following a low-carbohydrate diet. Because long-term dietary trials are complex and costly, we were especially interested in the experience of long-term diet adherents. Such research is hypothesis-generating and enables researchers to explore the actual lived experience of people following such a dietary approach.
The Low Carb Lifestyle Survey was a quality improvement project for the American Board of Family Physicians (ABFM), developed by Dr Mark Cucuzzella and with survey design assistance from collaborators in the United Kingdom (diabetes.co.uk).
The survey was shared with the American and international ‘low-carb’ community via social media and through international health care professionals who support therapeutic uses of low-carbohydrate diets. As Dr Cucuzzella has been recommending a low-carbohydrate diet as an option to his patients with T2D for 6 years, the survey was also shared with individual patients he sees and members of his local community.
The 57-question survey was administered on Survey Monkey (an online survey company); the survey was open from December 2016 to June 2017. The survey included closed-ended, multiple-choice and open-ended questions. Responses to the survey were kept confidential. The full 57-question survey can be viewed in supplemental materials (see
Where appropriate, we used chi-squared tests to compare proportions and paired
The American Board of Family Medicine (ABFM) peer-reviewed and approved the project before release. After results were collected, the ABFM again reviewed the project and determined that it met standards for a Quality Improvement (QI) project. A QI project relevant to the quality and standards of the ABFM is mandatory for maintenance of certification as a Board Certified Family Physician.
The survey was completed by 1580 respondents. Respondents were required to answer all questions, with the exception of the open-ended items. The majority of respondents resided in the United States, with the rest residing elsewhere (
Survey respondent characteristics.
Characteristic | |
---|---|
Female | 982 (62.2) |
Male | 598 (37.9) |
< 20 | 2 (0.1) |
20–29 | 34 (2.2) |
30–39 | 223 (14.1) |
40–49 | 483 (30.6) |
50–59 | 524 (33.2) |
60–69 | 266 (16.9) |
> 70 | 48 (3.0) |
American Indian or Alaskan Native | 12 (0.8) |
Asian or Pacific Islander | 36 (2.3) |
Black or African American | 25 (1.6) |
Hispanic or Latino | 58 (3.7) |
White/Caucasian | 1435 (90.1) |
Prefer not to answer | 10 (0.6) |
Other | 44 (2.8) |
USA | 919 (58.2) |
Canada | 128 (8.1) |
South and Central America | 15 (0.9) |
Europe | 289 (18.3) |
South Africa | 43 (2.7) |
Middle East | 16 (1.0) |
Asia and India | 18 (1.1) |
Australia and New Zealand | 152 (9.6) |
Full-time employment | 994 (63.0) |
Part-time employment | 171 (11.0) |
Currently not working | 146 (9.2) |
Retired | 238 (15.1) |
Student | 31 (2.0) |
Internet | 616 (39.0) |
Medical professional | 168 (10.6) |
Family member or friend | 315 (19.9) |
Book | 240 (15.2) |
Community group | 22 (1.4) |
Other | 10 (13.2) |
To improve chronic health condition | 696 (44.1) |
For weight loss | 1184 (75.0) |
To enhance athletic performance | 211 (13.4) |
To have more energy throughout day | 498 (31.5) |
Friend or family member on low-carbohydrate diet | 89 (5.6) |
No specific reason – just curious | 37 (2.3) |
Other | 334 (21.1) |
< 1 month | 34 (2.2) |
1–3 months | 185 (11.8) |
3–6 months | 180 (11.4) |
6 months–1 year | 298 (18.9) |
1–2 years | 347 (22.0) |
> 2 years | 536 (34.0) |
< 30 g | 780 (49.4) |
30 g–50 g | 502 (31.8) |
50 g–100 g | 252 (16.0) |
100 g–200 g | 42 (2.7) |
200 g–300 g | 4 (0.3) |
Minutes per week - Min (SD) | 164 (192) |
Almost half (49%) of the respondents reported a very restricted average carbohydrate intake of less than 30 g per day. Almost one-third (32%) reported an average carbohydrate intake of 30 g – 50 g per day, 16% reported 50 g – 100 g per day and the remaining 3% reported more than 100 g per day. Average carbohydrate intake was inversely associated with amount of time spent on the diet; that is, of those adherents for less than 6 months, 65% reported an average daily carbohydrate intake of less than 30 g. For participants adherent from 6 months to 2 years, daily consumption of less than 30 g daily still comprised the majority response, but had declined with time. By 2 years, those consuming less than 30 g daily and those consuming 30 g – 50 g daily were even at 38% each. This is consistent with one approach to carbohydrate restriction, starting with a very low-carbohydrate intake and then gradually increasing the carbohydrate level as time goes on.
The large majority of respondents reported weight loss and waist circumference reduction with a low-carbohydrate diet (
Weight and waist circumference loss in relation to carbohydrate intake.
Weight and waist circumference change with low-carbohydrate diet.
Type of Change | |
---|---|
Did not weigh | 32 (2.0) |
Weight stayed within 2 pounds of starting weight | 74 (4.7) |
Gained 2 or more pounds | 46 (2.9) |
Lost 2–10 pounds | 254 (16.1) |
Lost 10–30 pounds | 555 (35.1) |
Lost 30–50 pounds | 346 (21.9) |
Lost > 50 pounds | 273 (17.3) |
Did not measure | 280 (17.7) |
Gained waist circumference | 18 (1.1) |
Lost < 1 inch | 111 (7.0) |
Lost 1–3 inches | 512 (32.4) |
Lost 3–5 inches | 387 (24.5) |
Lost > 5 inches | 272 (17.2) |
Among respondents who knew their weight and waist circumference before and after diet initiation, at 6–12 months on the diet (
Weight and waist circumference loss in relation to time on a low-carbohydrate diet.
Lab test values before and after low-carbohydrate diet initiation.
Lab test values | Before, mean (SD) | After, mean (SD) | Difference, mean (SD) | ||
---|---|---|---|---|---|
Fasting blood glucose | 352 | 143 mg/dL (58.2) | 99 mg/dL (72.5) | 44.4 (66.2) | < 0.001 |
Postprandial blood glucose | 267 | 175 mg/dL (45.8) | 107 mg/dL (22.9) | 69.3 (67.6) | < 0.001 |
Total cholesterol | 221 | 210 mg/dL (47.5) | 232 mg/dL (59.9) | 21.9 (62.2) | < 0.001 |
LDL cholesterol | 221 | 127 mg/dL (44.0) | 144 mg/dL (55.6) | 16.9 (53.9) | < 0.001 |
HDL cholesterol | 221 | 57 mg/dL (21.1) | 71 mg/dL (24.4) | 14.6 (17.7) | < 0.001 |
Triglycerides | 221 | 149 mg/dL (144.3) | 82 mg/dL (55.3) | −67.7 (144.0) | < 0.001 |
Triglyceride/HDL ratio | 221 | 3.49 (4.62) | 1.37 (1.21) | −2.11 (4.44) | < 0.001 |
SD, Standard deviation; LDL, low-density lipoprotein; HDL, high-density lipoprotein.
Proportion of participants with HbA1c levels in the normal, pre-diabetes or type 2 diabetes ranges before and after initiation of a low-carbohydrate diet (
HbA1c | Before, |
After, |
|
---|---|---|---|
< 5.5 (Normal) | 82 (16.6) | 241 (65.3) | < 0.001 |
5.5–6.4 (Pre-diabetes) | 173 (34.9) | 137 (27.7) | < 0.001 |
> 6.5 (Type 2 diabetes) | 240 (48.5) | 35 (7.1) | < 0.001 |
We also examined the proportion of participants reporting HbA1c levels in the normal range or in the ranges diagnostic of pre-diabetes or T2D (
HbA1c values stratified by carbohydrate intake.
HbA1c value per carbohydrate intake level | Before initiation |
After initiation |
Chi-square statistic ( |
---|---|---|---|
6.5 or more | 139 (53.9) | 16 (6.2) | 203.5 (< 0.0001) |
5.5–6.4 | 88 (34.1) | 65 (25.2) | |
Under 5.5 | 31 (12.0) | 177 (68.6) | |
6.5 or more | 69 (45.1) | 14 (9.2) | 71.8 (< 0.0001) |
5.5–6.4 | 55 (35.9) | 45 (29.4) | |
Under 5.5 | 29 (19.0) | 94 (61.4) | |
6.5 or more | 28 (36.8) | 4 (5.3) | 30.7 (< 0.0001) |
5.5–6.4 | 28 (36.8) | 23 (30.3) | |
Under 5.5 | 20 (26.3) | 49 (64.5) | |
6.5 or more | 4 (50.0) | 1 (12.5) | 2.7 (0.26) |
5.5–6.4 | 2 (25.0) | 4 (50.0) | |
Under 5.5 | 2 (25.0) | 3 (37.5) |
Respondents reported declines in use of medications (e.g., antidepressant, anti-anxiety, sleep aids, pain relief, anti-inflammatory and phosphodiesterase type 5 inhibitors for erectile dysfunction) after starting the diet (
Medication use before and after low-carbohydrate diet initiation.
Medication type | Used before, |
Used after, |
|
---|---|---|---|
Antidepressant | 195 (12.5) | 90 (5.8) | < 0.001 |
Anti-anxiety | 112 (7.3) | 52 (3.4) | < 0.001 |
Sleep aids | 176 (11.4) | 74 (4.8) | < .001 |
Painkillers | 342 (22.1) | 77 (5.0) | < 0.001 |
Anti-inflammatory | 417 (27.1) | 101 (6.8) | < 0.001 |
Erectile dysfunction | 17 (1.1) | 13 (0.86) | 0.46 |
Small minorities of respondents reported current use of medications for diabetes, high blood pressure and hyperlipidaemia, with some reporting having reduced or completely discontinued such medications after initiating the diet (
Medication use.
Medication type | Currently use, |
Reduced or stopped since diet initiation, |
---|---|---|
Diabetes | 140 (8.9) | 107 (6.8) |
Blood pressure | 221 (14.0) | 178 (11.3) |
Cholesterol | 82 (5.2) | 93 (5.9) |
Respondents reported improvements in energy level (see
Energy level before and after a low-carb diet broken down by amount of time following a low-carb lifestyle.
Energy and activity, physical and emotional well-being before and after low-carbohydrate diet initiation.
Indicator | Before |
After |
|
---|---|---|---|
Low | 935 (59.2) | 41 (2.6) | < 0.001 |
Moderate | 579 (36.7) | 734 (46.5) | < 0.001 |
High | 66 (4.2) | 805 (51.0) | < 0.001 |
Slight or no problem | 1224 (77.5) | 1535 (97.2) | < 0.001 |
Moderate or severe problem | 347 (22.0) | 43 (2.7) | < 0.001 |
Unable to perform | 0 (0.6) | 2 (0.1) | > 0.15 |
Slight or no problem | 1302 (82.4) | 1531 (96.9) | < 0.001 |
Moderate or severe problem | 272 (17.2) | 47 (3.0) | < 0.001 |
Unable to walk | 6 (0.4) | 2 (0.1) | > 0.15 |
Slight or no pain or discomfort | 906 (57.3) | 1502 (95.1) | < 0.001 |
Moderate or severe | 650 (41.1) | 78 (4.9) | < 0.001 |
Extreme pain | 24 (1.5) | 0 (0) | < 0.001 |
Slight or no anxiety or depression | 1053 (66.7) | 1519 (96.1) | < 0.001 |
Moderate or severe anxiety or depression | 485 (30.7) | 60 (3.8) | < 0.001 |
Extreme anxiety or depression | 42 (2.7) | 1 (0.1) | < 0.001 |
Changes in physical and psychological well-being after starting low-carbohydrate diet.
Indicator | Improved, |
No change, |
Worsened, |
---|---|---|---|
General quality of life | 1461 (92.5) | 105 (6.7) | 14 (0.9) |
Quality of sleep | 1094 (69.2) | 433 (27.4) | 53 (3.4) |
Confidence in controlling blood sugar | 1019 (64.5) | 551 (34.9) | 10 (0.6) |
Motivation to maintain changes made in lifestyle | 1482 (93.8) | 87 (5.5) | 11 (0.7) |
Confidence in food choices | 1509 (95.5) | 57 (3.6) | 14 (0.9) |
Outlook on life | 1385 (87.7) | 184 (11.7) | 11 (0.7) |
Self-esteem | 1335 (84.5) | 240 (15.2) | 5 (0.3) |
Happiness | 1318 (83.4) | 247 (15.6) | 15 (1.0) |
Between-meal experiences.
Indicator | Experienced before, |
Experienced after, |
|
---|---|---|---|
Intense hunger | 1375 (87.1) | 55 (3.5) | < 0.001 |
Tiredness | 1480 (93.9) | 305 (19.3) | < 0.001 |
Difficulty concentrating | 1300 (83.0) | 177 (11.3) | < 0.001 |
Mood swings | 1160 (74.3) | 154 (9.8) | < 0.001 |
Irritability | 1251 (79.9) | 255 (16.3) | < 0.001 |
Anxiety | 925 (59.4) | 207 (13.3) | < 0.001 |
Respondents were invited to answer three open-ended questions about their experiences on a low-carbohydrate diet. Common responses are summarised in
Commonly reported free-response answers.
Have there been any other changes to your health that we have not already covered? (838 responses) | What is the most challenging aspect of the low carbohydrate lifestyle? (1302 responses) | What is the most important piece of information or learning that you have taken from the low carbohydrate lifestyle? (1226 responses) |
---|---|---|
Improvement in allergy symptoms and breathing quality | Holidays and special occasions | Insulin resistance and metabolic syndrome |
Improvement in athletic performance | Vacations and travelling | Sugar content of food |
Improvement in libido | Social occasions and dining out | Food’s effect on satiety |
Improvement in mental clarity | Negative reactions from family and friends | Self-importance |
Improvement in irritable bowel syndrome | Negative reactions from health professionals | Importance of non-scale victories |
Improvement in heartburn and acid reflux | Criticism and misunderstanding | Eating fat does not cause you to be fat |
Improvement in immune function | Initial ‘carbohydrate flu’ symptoms | Eating three meals a day is unnecessary |
Improvement in integument and dental quality | Leg cramps and electrolyte balance | Nutritional ketosis is different from ketoacidosis |
Improvement in polycystic ovary syndrome and menstruation | Work, financial and other life stressors | Eating meat is not something to feel guilty about |
Improvement in migraine frequency | Concerns about cholesterol | To pay attention to how one feels in response to food |
Improvement in joint pain and chronic pain | Desire for certain foods | Carbs are not needed to train for endurance races |
Improvement in NAFLD | None | Sugar cravings occur only when eating sugar |
NAFLD, non-alcoholic fatty liver disease.
To date, few studies have been published on the efficacy of low-carbohydrate diets for weight loss or reversal of metabolic syndrome and T2D beyond 2 years in duration.
An important marker of metabolic health and adverse long-term outcomes is a large waist circumference and visceral fat.
Although fewer than half (44.1%) of respondents reported that their reason for following a low-carbohydrate diet was to improve a chronic condition, we collected robust data for diabetes and glucose control. Of the entire cohort, 495 knew their HbA1c before diet initiation and 413 knew their value post-diet initiation. By definition, people with T2D have an HbA1c of ≥ 6.5, and pre-diabetes is defined by an HbA1c of 5.7–6.4. Many studies suggest that an HbA1c around 5.0–5.5 is likely to be the ideal.
Active management of diabetes requires measuring fasting and post-meal blood glucose levels. Average pre-diet values (143 mg/dL fasting and 175 mg/dL post-meal) reflected poor glucose tolerance (
It is clear in the literature that the most powerful predictor in a basic lipid panel of insulin resistance and cardiovascular health is the ratio of TG and HDL-cholesterol.
Our survey showed marked reductions in medication use and costs, which is an important finding not only for consumers but also for insurance companies and taxpayers. While more than half of the respondents said drug costs were not relevant for them, a quarter of respondents were able to reduce their individual costs, and in those with a specific amount cited, the average reduction was $288 a month.
Decreased strength and difficulty in mobility are associated with poor health outcomes and increased mortality.
Similarly, anxiety and depression are common primary care symptoms.
In this sample of successful, mostly long-term low-carbohydrate diet followers, the diet led to improvements in physical and psychological well-being for most of our study respondents. Feelings of emotional well-being are hypothesised to be important components for sustainable lifestyle change.
Moreover, participants reported improvements in a variety of health conditions after initiating a low-carbohydrate diet, some of which have been studied before, at least preliminarily (improvements in symptoms related to migraines,
This study was not without limitations. This was a retrospective study assessing a host of biomedical indicators reliant on self-reported data subject to recall bias. Although we believe that the questions we used are face valid, we did not use validated self-report scales. Therefore, some answers may not be as reliable and accurate as they would have been if we had used validated instruments. A detailed survey like this also lends itself to those who are highly engaged in the topic. Like any survey, the respondents may not be representative of all patients. Furthermore, in our appeal for participants, we did not differentiate between people who are followers of one of the many types of carbohydrate-restricted approaches such as low-carbohydrate, high-fat and low-carbohydrate, high-protein (although most of the practitioners who supported the survey favoured a low-carbohydrate, high-fat approach). As to the small sample of minorities, we feel this reflects, at least in part, the bias inherent in snowballing sampling. Many of the initial contacts when the survey was launched were not minority (non-white people comprise about 6% of the population of the state of West Virginia). As the survey was largely shared through social networks, it could be that race played a role in who was invited to take part.
Furthermore, this study lacked the rigour of a randomised, controlled trial. However, our goal was not to compare the results of a low-carbohydrate diet with some other dietary approach. Instead, we were interested in what people who were voluntarily choosing to follow some kind of carbohydrate-reduced nutritional approach would report about their lived experience.
The results of our survey support pursuit of other pertinent questions around myriad aspects of low-carbohydrate diets: long-term health effects, factors that facilitate success and overcoming of barriers, age-related differences in response to the diet and parameters of the optimal low-carbohydrate diet for overall health and well-being.
Currently recommended drug treatments, nutritional guidelines and behavioural interventions have had limited to no success in halting the obesity and diabetes epidemics. This has resulted in exorbitant health care costs
The authors declare that they have no financial or personal relationships which may have inappropriately influenced them in writing this article.
M.T.C. was responsible for project conception, design and implementation. J.T. assisted with project implementation, performed calculations and created figures and graphs. M.T.C. and J.T. wrote the initial draft. N.E.D. made conceptual and editorial contributions. L.S. was responsible for the aims section and made conceptual and editorial contributions. T.R.W. made conceptual and editorial contributions and reviewed calculations as well as directed the reference section.