Can the Ketogenic Diet Reverse Type 2 Diabetes?
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Exploring one of the major health claims made for
ketogenic diets, that they reverse insulin resistance and effectively treat
diabetes...
In this post, I’m going to explore one of the major health claims made
for ketogenic diets, that they reverse insulin resistance and effectively
treat diabetes.
Ketogenic Diets and Diabetes
Claims that ketogenic diets effectively treat diabetes are rife on the
Internet and in popular books. Keto enthusiasts claim that carbohydrate
consumption is the cause of the insulin resistance that drives type 2
diabetes[1].
Insulin resistance is known to be an important risk factor for the
development of the complications of diabetes[2], both microvascular –
diabetic eye (retinopathy), nerve damage (neuropathy) and kidney disease
(nephropathy) – and macrovascular – coronary artery disease, peripheral
artery disease, and stroke. Ketogenic diet advocates argue[3], removing
carbohydrates from the diet effectively treats the cause of diabetes and its
complications: “insulin resistance functionally manifests itself as
‘carbohydrate intolerance’. When dietary carbohydrate is restricted to a
level below which it is not significantly converted to fat (a threshold that
varies from person to person), signs and symptoms of insulin resistance
improve or often disappear completely”.
Children and young adults put on ketogenic diets to manage epilepsy were
found to have higher arterial stiffness parameters, an early marker of
vascular damage.
There are certainly studies which demonstrate the effectiveness of
ketogenic diets for reducing various markers of diabetic control. For
example, one study[4] compared a ketogenic diet with “unlimited amounts of
animal foods (i.e., meat, chicken, turkey, other fowl, fish, shellfish) and
eggs, limited amounts of hard cheese (e.g., cheddar or swiss, 4 ounces per
day), fresh cheese (e.g., cottage or ricotta, 2 ounces per day), salad
vegetables (2 cups per day), and non-starchy vegetables (1 cup per day)” to
a low-glycemic, reduced-calorie diet and found the ketogenic diet superior
in reducing blood glucose, hemoglobin A1C, and fasting insulin levels along
with reductions in injected insulin and oral diabetes medications.
But there are multiple lines of evidence contradicting the ‘carbs cause
diabetes, so low-carb cures diabetes’ belief.
What Does the Science Say?
First, most intervention studies on ketogenic diets are short-term, but the
limited evidence available from studies with longer follow-up periods
indicates that the beneficial effects of ketogenic diets on biomarkers
dissipate over time, long-term adherence is difficult, and there are higher
rates of kidney stones, osteoporosis and hyperlipidemia[5].
Then there are epidemiological, or population-based studies, which
consistently demonstrate that reducing carbohydrate intake increases the
risk of diabetes:
- The rate of type 2 diabetes in China rose from 2.6% in 2000 to 9.7% in 2010,
with the most dramatic rise occurring in urban areas[6]. But rice and other
grain intake has dropped dramatically in China over that time, while oil and
animal product intake rose – as did obesity rates[7].
- Likewise, indigenous Mexican communities such as the Tepehuano, Huichol and
Mexicanero were found to have zero diabetes just before the turn of the 20th
century, while eating an extremely high carbohydrate diet consisting mostly
of unrefined corn, beans, rice and squashes[8]. Pima Indians living in
Mexico on high in complex carbohydrate diets deriving on average 25% of
energy from fat and 11% from protein, have less than one-fifth the
prevalence of diabetes[9] compared to Pima living in the US on a higher fat
and protein diet.
- The Health Professionals Follow-Up Study tracked over 40,000 US men who were
free of type 2 diabetes at baseline for up to 20 years, and found that those
who ate a low-carbohydrate diet rich in animal fat and protein were 37% more
likely to develop diabetes10].
- Vegans – who naturally eat a high-carbohydrate diet – were found to have
half the risk of developing type 2 diabetes as meat-eaters, even after
adjusting for physical activity and body mass index[11]; in other words,
even overweight, and sedentary vegans had a reduced risk of diabetes due to
eating carbohydrate-rich plants!
In intervention studies, low-fat plant-based diets have been found to be
superior to conventional diabetes diets which restrict carbohydrate intake.
- Diabetic men on insulin therapy were confined to a metabolic ward and were
fed a restricted carbohydrate diet typically recommended to diabetics (20%
protein, 43% carbohydrate, 37% fat), followed by a very low fat, high
carbohydrate and high in plant fiber diet (21% protein, 70% carbohydrate, 9%
fat) for the remainder of the study[12]. Participants were instructed to eat
more if they lost weight on the high carbohydrate diet to factor out the
effect of weight loss on insulin sensitivity. As a result, every single
patient reduced his daily dose of insulin while on the high carbohydrate
diet, from an average of 26 units per day to 11 units per day, and several
were able to discontinue insulin altogether. Despite the reduction in
insulin, fasting and postprandial plasma glucose values were lower in most
patients on the high carbohydrate diet than on the standard diabetes diet.
- In a 74-week clinical trial comparing a low-fat whole food, plant-based diet
to a diet conforming to American Diabetes Association guidelines, the
plant-based diet improved blood sugar and lipid levels more than
conventional diabetes dietary recommendations[13].
- A systematic review of studies using plant-based diets for diabetes[14]
found that they significantly improved glycemic control, despite (or perhaps
because of) increases in carbohydrate intake by, on average, 14% of energy,
while decreasing fat by 12%.
What Drives Insulin Resistance – Carbohydrates or Fat?
It’s been known since the 1930s that dietary fat decreases insulin
sensitivity[15] – or to put it another way, causes insulin resistance. Among
the various types of dietary fat, the saturated type found mostly in animal
products but also in coconut and palm oils has the worst effect on insulin
sensitivity. Epidemiological studies indicate that “subjects with higher
intakes of fat are more prone to develop disturbances in glucose metabolism,
type 2 diabetes or impaired glucose tolerance, than subjects with lower
intakes of fat.” Additionally, experimental studies clearly demonstrated
that diets high in fat impaired insulin sensitivity, while diets low in fat
but high in carbohydrates improved it[16].
The underlying mechanism in insulin resistance is characterized by
accumulation of lipids (fats) in muscles, the liver and eventually the
pancreas:
- Muscles take up free fatty acids from the bloodstream to use as fuel, and
will take up more when fat is the primary macronutrient in the diet.
However, when dietary fat intake is persistently high, they begin to
accumulate more fat than they can oxidize (burn as fuel), and this
intramyocellular lipid accumulation results in the muscle cells becoming
insulin resistant[17].
- Insulin resistance in muscular tissue increases fat deposition in the liver,
causing the liver to become insulin resistant too[18]. This hepatic insulin
resistance drives the liver to continually release glucose and raises
triglycerides (fats) levels in the bloodstream, worsening the fatty liver.
- Because of the insulin resistance in the muscles and the liver, the pancreas
is initially forced to produce and secrete more insulin. But then the higher
levels of circulating triglycerides begin to also cause fat accumulation in
and around the pancreas, killing off the insulin-secreting beta cells
(“lipotoxicity”) and eventually resulting in inadequate insulin production.
At this point, blood glucose levels rise and the symptoms of type 2 diabetes
occur.
These 3 pathological manifestations of insulin resistance are driven by
‘positive energy imbalance’[19] – that is, consuming more energy than we use
in our daily activities. A whole food, plant-based diet – high in unrefined,
complex carbohydrates and low in fat – is the most effective dietary intervention for long-term weight loss
published in a peer-reviewed journal[20]. Even when instructed to eat ad
libitum (that is, until they were full, with no portion control) and without
being asked to increase their exercise level, overweight and obese
participants in the BROAD Study were able to achieve average weight losses
of 12 kg in 1 year.
Which Diet Is Best for the Long-Term Health of Diabetics?
Finally, it’s important to note that diabetics don’t die of diabetes per se;
they die from its complications. The major cause of death in diabetics is
cardiovascular disease, and a low-fat, whole food, plant-based diet is the
only diet shown to reverse coronary artery disease[21].
On the other hand, children and young adults put on ketogenic diets to
manage epilepsy were found to have higher arterial stiffness parameters[22],
an early marker of vascular damage. This fact alone should be enough warning
about the long-term risks of ketogenic diets, and encourage the use of
low-fat, plant-based diets as the gold standard for diabetes management.
In summary, human populations living on high in complex carbohydrate,
low-fat diets comprised primarily of minimally processed plant foods have
historically enjoyed extremely low rates of diabetes. When they make the
‘epidemiological transition’ to a Western-style diet, which inevitably means
a reduction in complex carbohydrates and an increase of animal and refined
plant foods (including fats, oils, flour and sugar), their diabetes rates
soar.
While ketogenic diets may lead to temporary improvements in glycemic
control, they lose their effectiveness over time, are fundamentally
unnatural to humans, and are unable to prevent the life-threatening
complications of diabetes.
Why take the risk of a ketogenic diet, when a whole food, plant-based diet
is a delicious, sustainable and proven method of preventing, managing, and
even reversing diabetes?
References
- Taylor, R. (2012), Insulin Resistance and Type 2 Diabetes. Diabetes 61(4)
778-779. http://diabetes.diabetesjournals.org/content/61/4/778
- Donga, E., Dekkers, O.M., Corssmit, E.P.M. & Romijn, J.A. (2015), Insulin
resistance in patients with type 1 diabetes assessed by glucose clamp
studies: systematic review and meta-analysis. Eur J Endocr
- Paoli, A., Rubini, A., Volek, J.S. & Grimaldi, K.A., (2013), Beyond weight
loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic)
diets. Eur J Clin Nutr.;67(8):789-96.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3826507/
- Westman, E.C., Yancy, W.S., Mavropoulos, J.C., Marquart, M. & McDuffie,
J.R., (2008), The effect of a low-carbohydrate, ketogenic diet versus a
low-glycemic index diet on glycemic control in type 2 diabetes mellitus.
Nutr Metab.;5:36. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633336/
- Kosinski, C. & Jornayvaz, F.R., (2017), Effects of Ketogenic Diets on
Cardiovascular Risk Factors: Evidence from Animal and Human Studies.
Nutrients.;9(5):517. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5452247/
- Li, H., Oldenburg, B., Chamberlain, C., O’Neil, A., Xue, B., Jolley, D.,
Hall, R., Dong, Z. & Guo, Y., (2012), Diabetes prevalence and determinants
in adults in China mainland from 2000 to 2010: a systematic review. Diabetes
Res Clin Pract.;98(2):226-35. https://www.ncbi.nlm.nih.gov/pubmed/22658670
- Wang, H. & Zhai, F., (2013). Programme and policy options for preventing
obesity in China. Obes Rev.;14 Suppl 2(0 2):134-40.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4048452/
- Guerrero-Romero, F., Rodríguez-Morán, M. & Sandoval-Herrera, F., (1997), Low
prevalence of non-insulin-dependent diabetes mellitus in indigenous
communities of Durango, Mexico. Arch Med Res.;28(1):137-40.
https://www.ncbi.nlm.nih.gov/pubmed/9078601
- Schulz, L.O., Bennett, P.H., Ravussin, E., Kidd, J.R., Kidd, K.K., Esparza,
J. & Valencia, M.E., (2006), Effects of traditional and western environments
on prevalence of type 2 diabetes in Pima Indians in Mexico and the U.S. Diab
Care;29(8):1866-71. https://www.ncbi.nlm.nih.gov/pubmed/16873794
- de Koning, L., Fung, T.T., Liao, X., Chiuve, S.E., Rimm, E.B., Willett,
W.C., Spiegelman, D., & Hu, F.B., (2011), Low-carbohydrate diet scores and
risk of type 2 diabetes in men. Am J Clin Nutr.;93(4):844-50.
https://www.ncbi.nlm.nih.gov/pubmed/21310828
- Tonstad, S., Butler, T., Yan, R. & Fraser, G.E., (2009), Type of vegetarian
diet, body weight, and prevalence of type 2 diabetes. Diab
Care.;32(5):791-6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671114/
- Anderson, J.W. & Ward, K., (1979), High-carbohydrate, high-fiber diets for
insulin-treated men with diabetes mellitus. Am J Clin Nutr.;32(11):2312-21.
https://www.ncbi.nlm.nih.gov/pubmed/495550
- Barnard, N.D., Cohen, J., Jenkins DJ, et al. (2009), A low-fat vegan diet
and a conventional diabetes diet in the treatment of type 2 diabetes: a
randomized, controlled, 74-wk clinical trial. Am J Clin Nutr.
2009;89(5):1588S-1596S.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2677007/
- Yokoyama, Y., Barnard, N.D., Levin, S.M. & Watanabe, M. (2014), Vegetarian
diets and glycemic control in diabetes: a systematic review and
meta-analysis. Cardiovasc Diagn Ther.;4(5):373-82.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4221319/
- Lichtenstein, A.H. & Schwab, U.S. (2000), Relationship of dietary fat to
glucose metabolism. Atherosclerosis;150(2):227-43.
https://www.ncbi.nlm.nih.gov/pubmed/10856515
- Himsworth, H.P., (1934), Dietetic factors influencing the glucose tolerance
and the activity of insulin. J Physiol.;81(1):29-48.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1394223/
- Kraegen, E.W. & Cooney, G.J., (2008), Free fatty acids and skeletal muscle
insulin resistance. Curr Opin Lipidol.;19(3):235-41.
https://www.ncbi.nlm.nih.gov/pubmed/18460913
- Taylor, R. (2008), Pathogenesis of type 2 diabetes: tracing the reverse
route from cure to cause. Diabetolog.;51(10):1781-9.
https://www.ncbi.nlm.nih.gov/pubmed/18726585
- Ibid.
- Wright, N., Wilson, L., Smith, M., Duncan, B. & McHugh, P., (2017), The
BROAD study: A randomised controlled trial using a whole food plant-based
diet in the community for obesity, ischaemic heart disease or diabetes. Nutr
Diabetes. 7(3):e256. https://www.ncbi.nlm.nih.gov/pubmed/28319109
- Ornish, D., Scherwitz, L.W., Billings, J.H., Brown, S.E. et al (1998),
Intensive lifestyle changes for reversal of coronary heart disease.
JAMA;280(23):2001-7. https://www.ncbi.nlm.nih.gov/pubmed/9863851
- Kossof, E., (2014), Danger in the pipeline for the ketogenic diet? Epilepsy
Curr.;14(6):343-4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4325592/
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