Picture this: a thick, juicy, tender eventeak grilled to perfection with melted butter glazed on top, gently dripping down the sides. Lying next to the steak there’s a side of dark green asparagus sautéed in coconut oil and dusted with a sprinkle of sea salt. Could a diet loaded with fat help you lose diet-resistant body fat that’s been taunting the seams of your dress pants and poking through buttons on your shirt? Will eating fat turn you into an all-star athlete? This is part 1 of a 2 part series on the ketogenic diet.
Here is what I will cover in this blog post:
- What is the ketogenic diet?
- Adverse health effects.
Here is what I will cover in tomorrow’s blog on this topic:
- The issue with ketogenic research studies.
- Is the ketogenic diet superior for losing fat?
- How will the ketogenic diet affect muscle?
- How will the ketogenic diet impact athletic performance?
What is the Ketogenic Diet?
For nearly a century, epileptic patients have used ketogenic diets to control seizures when common medications provide no relief. Scientists aren’t sure why following a ketogenic diet decreases the incidence and severity of seizures but it works.
The ketogenic diet contains – 80-90% of calories from fat, 15% from protein and 5% from carbohydrate (1, 2). Food choices may include heavy cream, bacon, eggs, non-starchy vegetables, mayonnaise and sausage while fruits, starchy vegetables, breads, pasta, cereal and other carbohydrate-rich foods are not allowed.
During the first several days on a ketogenic diet, your body’s limited supply of carbohydrate stored in liver and muscle tissue decreases dramatically. As a result, you will feel like you have mono – exhausted, with headaches and easy exercise will feel like you’re climbing Mount Everest (3). Once your stored carbohydrate has dwindled, ketones, formed from the breakdown of dietary fat, become the primary source of energy for brain and body. Ketogenic means “ketone forming.” It takes at least seven days to reach nutritional ketosis and several weeks to fully adapt to the diet (12). If you aren’t in nutritional ketosis (as measured by blood, urine or breath ketones; ketone levels > 0.5 mmol/L), then you aren’t following a ketogenic diet, you are on a low carbohydrate diet.
Adverse Health Effects from the Ketogenic Diet
Much of the research on adverse effects comes from studies in epileptic children since they have been on the diet for long periods of time. These studies show soon after starting a ketogenic diet, blood cholesterol levels and artery stiffness increase (4, 5). High total and LDL cholesterol are risk factors for cardiovascular disease (diseases of the heart and blood vessels). When arteries are stiff, they cannot expand as well in response to changes in blood pressure. Think of this like a garden hose when you turn up the water pressure, your hose either expands or the water bursts out of the space between the faucet and the hose. When arteries cannot open widely to accommodate increases in blood flow, blood pressure increases leading to microscopic tears on artery walls, development of scar tissue and the perfect surface for plaque buildup (6). Blood cholesterol levels returned to normal in patients who went off the diet and in those who stayed on it, they returned to normal after 6 to 12 months. Artery stiffness returned to normal after 24 months on a ketogenic diet.5 Studies in obese patients suggest ketogenic diets improve blood sugar and blood cholesterol levels over time, either due to the diet, weight loss from the diet, a combination of the two or carbohydrate restriction (7, 8). Lose weight, regardless of what you eat and blood cholesterol, blood pressure, inflammation, blood sugar and many other disease risk factors will improve.
Ketogenic diets are typically low in calcium, vitamin D, potassium, magnesium, folic acid and fiber. There are several potential consequences associated with consistently low intake of each of these micronutrients including softening of the bones, decreased bone density, muscle damage, muscle weakness or spasms, and abnormal heart rhythm. However, with careful planning, a fiber supplement, multivitamin and under the guidance of a physician who may prescribe potassium and sodium supplements (blood sodium could drop to dangerously low levels while on this diet), nutrient needs can be met. Also, to prevent constipation when on a ketogenic diet, a fiber supplement may be necessary along with more water / fluid intake then you are used to.
Here are some other potentially bad side effects from following a high fat diet:
- Harm to your Brain. Studies in mice show a high fat diet, even when followed for as little as two months leads to chronic inflammation, sedentary immune cells in the brain – these cells typically act like janitors picking up trash and infectious compounds but when they become sedentary they stop doing their job, leading to cognitive impairment (9). Does this happen in humans and resolve over time? We don’t know.
- Mad Bacteria in Your Gut. A diet with no probiotics (healthy bacteria) and low in prebiotics (certain types of fiber that the healthy bacteria much on for food keeping them happy) will likely change the composition of bacteria in your gut so you have more harmful and less beneficial bacteria.
- Leaky Gut. High saturated fat meals increase bacterial toxins (endotoxins) in the intestines and intestinal permeability. In other words: leaky gut (10, 11). If you are on this diet, consider opting for foods lower in saturated fat and higher in unsaturated fats (liquid oils, avocado, nuts, seeds, olives).
- Free radicals in overdrive? If you can’t eat a number of colorful foods including blueberries, beets, corn, oranges, and more, chances are you won’t get a wide array of antioxidant compounds to quench free radicals (compounds that are important for good health but can wreck your body when they aren’t tamed by antioxidants) as well as other plant-based compounds that keep your arteries, muscles and other parts of your body healthy. Will your body adapt? We don’t know at this time.
Are the side effects and potential negative side effects worth it if you can lose weight on this diet? Stay tuned for tomorrow’s post on how the ketogenic diet impacts body fat and athletic performance.
1 Freeman JM, Freeman JB, Kelly MT. The ketogenic diet: a treatment for epilepsy. 3rd ed. New York, NY: Demos Health; 2000.
2 Paoli A, Bianco A, Damiani E, Bosco G. Ketogenic Diet in Neuromuscular and Neurodegenerative Diseases. BioMed Research International 2014, Article ID 474296, 10 pages, 2014.
3 White AM, Johnston CS, Swan PD et al. Blood ketones are directly related to fatigue and perceived effort during exercise in overweight adults adhering to low-carbohydrate diets for weight loss: a pilot study. J Am Diet Assoc 2007;107(10):1792-6.
4 Tanakis M, Liuba P, Odermarsky M, Lundgren J, Hallböök T. Effects of ketogenic diet on vascular function. Eur J Paediatr Neurol 2014;18(4):489-94.
5 Coppola G, Natale F, Torino A et al. The impact of the ketogenic diet on arterial morphology and endothelial function in children and young adults with epilepsy: a case-control study. Seizure 2014;23(4):260-5.
6 Cecelja M, Chowienczyk P. Role of arterial stiffness in cardiovascular disease. JRSM Cardiovascular Disease 2012;1(4):1-10.
7 Dashti HM, Mathew TC, Hussein T, Asfar SK, Behbahani A, Khoursheed MA, Al-Sayer HM, Bo-Abbas YY, Al-Zaid NS. Long-term effects of a ketogenic diet in obese patients. Exp Clin Cardiol 2004; 9(3): 200–205.
8 Volek JS, Feinman RD. Carbohydrate restriction improves the features of Metabolic Syndrome. Metabolic Syndrome may be defined by the response to carbohydrate restriction. Nutr Metab (Lond) 2005;2:31.
9 Hao S, Dey A, Yu X, Stranahan AM. Dietary obesity reversibly induces synaptic stripping by microglia and impairs hippocampal plasticity. Brain Behav Immun 2016 Jan;51:230-9.
10 Mani V, Hollis JH, Gabler NK. Dietary oil composition differentially modulates intestinal endotoxin transport and postprandial endotoxemia. Nutr Metab (Lond) 2013; 10: 6.
11 Lam YY, Ha CW, Campbell CR, Mitchell AJ, Dinudom A, Oscarsson J, Cook DI, Hunt NH, Caterson ID, Holmes AJ, Storlien LH. Increased gut permeability and microbiota change associate with mesenteric fat inflammation and metabolic dysfunction in diet-induced obese mice. PLoS One 2012;7(3):e34233.
12 Paoli, A, Grimaldi K, D’Agostino D, Cenci L, Moro T, Bianco A, Palma A. Ketogenic diet does not affect strength performance in elite artistic gymnasts. J Int Soc Sports Nutr 2012;9:34.