Disclaimer: this article is not intended to replace the recommendations of a qualified dietician. Before drastically changing your diet consult your healthcare practitioner.
Definition of a ketogenic or low carb diet:
A diet that is high in fat and protein and low in carbohydrates. This is usually measured at anywhere between 20-100g carbohydrates a day (with most people finding that they reach ketogenesis at 40-50g per day).
People often look to a ketogenic diet in order to drop body fat, as the idea is that the diet will cause you to start using your fat stores for energy.
When you are on a ketogenic diet, your body is running on ketones (produced from fat as an energy source) instead of its preferred source, carbohydrate. Most people will aim for 2 weeks to 6 months on this diet to trigger fat loss, and experts say that the fat-burning process triggered in the body is beneficial beyond the length of the ketogenic diet.
Benefits:
1. Less hunger:
Hunger tends to sabotage people’s best efforts to adhere to any diet. In reducing carbohydrates, the body is taking in food that requires longer to digest: protein and fat. People that eat less carbohydrates tend to eat less calories overall, which is great news if you are dieting since one of the main side effects of reducing daily calories is hunger.
2. More stable blood sugar levels:
Reducing intake of carbohydrates also reduces the need for the body to secrete insulin. Insulin is released in response to simple sugars, which is what carbohydrate is broken into during digestion. This release of insulin minimizes the impact of toxicity from elevated blood sugar as insulin shuttles the glucose into cells for storage or immediate energy.
3. More rapid weight loss:
Glycogen stored in the body tends to hold more water with it, therefore you tend to weigh more when you have a higher intake of carbohydrates. Low carb diets also tend to lower insulin levels which allows the kidneys to reduce the amount of excess sodium and therefore the body sheds more stored water weight.
Low carb dieters were found to lose double or triple1 the amount of weight compared to low fat dieters, and the only difference in retaining the weight lost is whether the participant can follow it longer term.
4. Lead to more weight loss from abdominal fat
Low carb diets don’t just experience more weight loss: the weight loss comes from the dangerous fat (visceral fat) that is stored around the organs2. The presence of this kind of fat tends to be related to metabolic disorders, inflammation in the body and insulin resistance.
5. Reduced triglycerides and increased High Density Lipoprotein (HDL), which carries the good cholesterol
Circulating triglycerides (fat) are the predictor for heart disease. Low fat diets cause increased triglycerides in the blood (whereas low carb diets reduce them), and a greater ratio of HDL to Low Density Lipoprotein (LDL), another heart disease predictor. HDL is the carrier for cholesterol to the liver to be processed (which is good), and LDL takes them from the liver and puts them into the body. By eating more fat, the HDL increases meaning that low fat diets are less beneficial to prevent heart disease.
6. Lowered blood pressure
In reducing blood pressure, you reduce your risk of heart disease, stroke, and many other chronic and debilitating diseases, which reduce your lifespan and quality of life.
7. Good for metabolic health
Fatty acids are essential for the absorption of many vitamins and for many healthy processes in the body. Low fat diets can often lead to metabolic issues, whereas a diet that is low in carbohydrates and higher in the macronutrients that the body requires a certain level of  (protein and fat) tends to help address issues.
Risks:
1. Constipation (from too little fiber):
Due to being lower in carbs, high fat diets don’t tend to be high in fiber which is found in carbs. Fiber keeps you “regular”. Try to include fibrous but low carb foods, such as pumpkin and avocado.
2. Its hard to follow (social life can suffer)
Not many restaurants and so called comfort foods are high fat and also low carb, making eating out with friends and family a challenge if you wish to follow the diet long term. Try asking for what you would usually eat as a modification of a menu item, and swap the dessert for coffee so that you don’t have to forgo the event entirely.
3. You are slower on energy
The body and brains preferred energy source is glycogen from carbohydrates, simply because glycogen is faster used as a source of energy. Fats instead require more steps in processing to be used for energy so therefore slow your recovery ability in the session. Try timing the carbs that you do have around your workout in order to get the most from your session.
4. It’s easier to overeat calories
High fat foods are very calorie dense: one gram of fat has nine calories, whereas one gram of carbohydrate has four (less than half). Overeating calories surplus to requirements will still cause you to gain weight despite its source, and that’s easier to do when less food is more calories. Try to only eat until you are satisfied, and if needed look up foods in MyFitnessPal or similar when you commence this diet to get your head around portion sizes.
5. It’s not optimal for athletic performance or for building muscle
Eating carbohydrates is extremely anabolic. If you seriously reduce carbohydrates, you reduce the muscle-building potential from your session, and you will find it harder to have an intense session as a result of lower energy from the body’s preferred energy source. Again, timing your carbs around training can help.
6. Ketogenic “flu”
Many people experience a sickness/sluggishness when they commence the keto diet as the body attempts to adjust to fat as a fuel source. This is temporary, but can be inconvenient for productivity. Try drinking lots of water, getting plenty of rest and easing your way into the full keto approach.
7. Gut bacteria might suffer
Gut microbiome rely on fiber, which is potentially reduced in low carb diets as most pre biotic foods are rich in carbohydrates. Try adding low carb prebiotic vegetables to your diet, such as kimchi and other fermented foods.
As you can see, there are a lot of benefits and some risks to considering a low(er) carb diet and including higher levels of fat in place of the carbs. However nutrition is not a one size fits all approach: whatever you find most convenient to follow long term is what determines the most effective diet for you.
Higher fat foods that are great choices to include on a ketogenic diet:
Seeds and nuts
Coconut oil
Dark chocolate
Egg yolk
Angus fillet
Bacon
Pork crackling
Pork belly
Nut butters
Avocado
Olives
If you're interested in how certain diets affect you and your health, read this for high-protein diets, this for the concept of reverse dieting, and this for the best diet for weight loss in women.
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