The ketogenic diet has traditionally been used to control seizures in children and adults with epilepsy, but lately it has been gaining popularity as a weight loss diet.
A ketogenic diet is high in fat, moderate in protein, and very low in carbohydrate (<30 grams per day). When the body is not getting adequate carbohydrates, it breaks down its own fat stores. Fat is converted in the liver to ketones, an alternate source of fuel. The process of the body breaking down fat for energy is called ketosis. To lose weight more effectively, you must adhere strictly to the very low carbohydrate diet to stay in a lower level of ketosis. If you are starting (or re-starting) a ketogenic diet, it can take a few days to a month for your body to switch to using ketones as its main fuel source.
This very low carbohydrate diet limits the intake of fruit, root vegetables, whole grains, milk, legumes and lentils, in addition to sweet treats and sugary beverages. Foods that may be consumed include: full fat dairy products such as butter, cream, whipped cream, cream cheese, sour cream, high fat yogurt and cheese; bacon, eggs, meat (including the fat), fish, poultry (including skin); and high fat sauces and oils (including coconut oil).
The main attraction of the ketogenic diet is the rapid, short-term weight loss compared with other calorie-restricted, low fat diets and a decrease in appetite. However, there does not seem to be much of a difference compared to calorie-restricted, low fat diets when it comes to long term weight loss.
This diet has been shown to have other benefits such as increasing levels of HDL (healthy cholesterol) and lowering triglycerides. The effect on LDL (unhealthy) cholesterol, a risk factor for heart disease, seems to vary. It may have no effect, increase or sometimes decrease LDL cholesterol. In people with type 2 diabetes, the ketogenic diet has been shown to improve blood glucose control and lower blood pressure. Some people also claim that they have more energy and improved mental clarity when following the diet.
When starting the ketogenic diet, for about the first week, you may experience flu-like symptoms such as fatigue, dizziness, headaches, nausea, brain fog/confusion and irritability. This may be due to the excess loss of fluid and electrolytes initially.
Other symptoms that you may experience during the adaptation period of a few weeks are: reduced physical performance, cravings, heart palpitations, insomnia, bad breath (fruity, metallic taste), leg cramps, constipation, hypoglycemia, hair loss and excess ketosis.
Since this diet is very restrictive, vitamin and mineral deficiencies may occur. There are concerns that the ketogenic diet may also have a negative effect on bone metabolism. This diet has also been associated with an increased risk of kidney stones.
It is recommended that you consult with your physician before starting the ketogenic diet and ongoing monitoring is advised. The long-term safety and effects of this diet is not yet known. This type of diet is not recommended for conditions such as kidney or liver disease, type 1 diabetes, pregnant or breastfeeding women.
If you choose to follow a ketogenic diet, it is recommended that you ensure that you are getting adequate fibre by consuming plenty of low-starch vegetables, some allowed fruits as well as low carbohydrate nuts and seeds. It is important to consume adequate fluids and electrolytes (especially initially) to combat the flu-like symptoms and stay hydrated. You should drink at least 6-8 glasses of fluid per day. When following this diet, healthier, plant-based fats such as olive oil and avocado should be substituted for animal fats. Plant-based proteins such as low carbohydrate nuts and seeds, 100% natural nut butters and high omega 3 fatty fish such as salmon, mackerel, herring and trout, would also be a healthier option. A vitamin/mineral supplement may be necessary if you are not meeting your nutritional needs through diet.
Low carbohydrate diets for weight loss are nothing new. The Atkins diet (though higher in protein) and others like it, have been very popular since the 1970’s. As with any diet that is very restrictive, most people find it impractical and difficult to maintain long term. Over time, foods that you enjoy start to make their way back into your diet and before you know it, you have gained back any weight you may have lost, and then some. These types of fad diets set people up for a life time of “yo-yo dieting”.
Most health care professionals agree that following a healthy, “balanced” diet with all the food groups is the most realistic and sustainable long term. A Mediterranean-type diet has been shown to have many health benefits such as:
reducing risk of developing heart disease
lowering blood cholesterol levels
lowering blood pressure
improving blood glucose (sugar) control for individuals with type 2 diabetes.
A Mediterranean-type diet includes plenty of vegetables and fruits, whole grains, plant-based protein such as legumes, lentils, nuts and seeds, high omega-3 fatty fish, poultry (without skin), lean meat (less often), low-fat milk products and healthy fats such as olive oil, avocado and 100% nut butters. Consuming more fresh, whole, natural foods and limiting sugars and highly refined, processed foods is also recommended for good health. Healthy eating can still include foods you enjoy in moderation. If your goal is to lose weight, a Registered Dietitian can help you learn how make healthier choices, eat in response to your hunger cues and identify and manage problematic eating behaviour. With effective weight loss counselling, you will be able to make healthy and enjoyable lifestyle changes and work toward achieving your long-term health goals.
Eat Well, Feel Well, Be Well
Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T, Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr. 2013 Oct; 110(7):1178-87.
Santos FL et al, Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors, Obesity Reviews, 2012, 1-19
Sofi F et al, Adherence to Mediterranean diet and health status: meta-analysis. BMJ 337:a1344, 2008.
Esposito K et al, Prevention and control of type 2 diabetes by Mediterranean diet: a systematic review. Diabetes Res Clin Pract 89:97–102, 2010