The ketogenic diet has recently become very popular because it can get you healthier and get the weight off better than many diets out there. To do a ketogenic diet requires a change in mindset to eating foods high in fat, but these should be good fats. In addition, too many carbohydrates (carbs) can mess up a ketogenic diet.


To force your body into ketosis, or a fat-burning mode, you must change your metabolism from a carb-burning mode, which actually deposits more fat into your fat cells; i.e. carbs feed fat. If you eat more fats, this turns off the mechanism of feeding the fat while burning fat for fuel. In order to keep this metabolism going, there are some foods that need to be avoided when doing a ketogenic diet. Here are some.



Foods like deserts, candy, and sugar products are essentially a no no when it comes to ketogenic diets. Once they go into your body, the sugar is immediately absorbed and raises blood sugar levels rapidly. Your body’s response to this is to secrete insulin from the pancreas.


Insulin is needed for your cells to utilize glucose. Without insulin, your cells essentially cannot use glucose well. If one looks at juvenile diabetics, who do not produce insulin, their bodies cannot utilize glucose well because their pancreas does not produce insulin. The result is that, before the advent of insulin, they would not thrive and would die at a young age. Luckily, today they can live a normal life with insulin injections.


However, too many sweets results in too much insulin production and your cells absorb more and more glucose. If you don’t use them for energy expenditure, i.e. exercise or activities, insulin has a second duty of storing the glucose inside your fat cells in the form of triglycerides. Thus, when you eat too many sweets, you’re actually feeding your fat!


Doing so switches your body into utilizing sweets for your energy needs instead of the stored fat. The result is you can become overweight and obese if this process continues to happen. In order to reverse this process, you must change your metabolism to burning fat. Once you’ve done this, with a ketogenic diet, if you don’t eat more than your basal metabolic needs, then you start burning your fat and you lose weight or can maintain a more normal body weight.


2.Carbohydrates (carbs)

Carbohydrates are in foods that are in many of our normal foods. To force your body into ketosis, i.e. a fat burning mode, you must limit or omit most foods containing a high carbohydrate load. The following are examples of these foods:

  • Grains: bread, crackers, cereal, pasta
  • Dairy: milk, yogurt, ice cream
  • Fruit: whole fruit, fruit juices
  • Legumes: beans


These foods can be eaten on a ketogenic diet, but the amounts must be decreased markedly. During a ketogenic diet, you should ingest less than 50 gm of carbohydrates per day. Thus, small portions of fruits can indeed be ingested, you just have to limit their amounts in order to stay in ketosis.


When purchasing foods, check the carb level in the portion of foods. There are foods in these categories that you can eat that contain lower amounts of carbs and with high fiber contents. Another concept of a ketogenic diet is to eat foods high in fiber. In fact, another way of calculating the foods you eat on a ketogenic diet is to use Net carbs, which is the grams of carbs minus the grams of fiber in a portion of the food. In this case, you want to total less than 20 to 30 Net grams of carbs per day.


For example, there are some pita breads that are low carb; some contain only 1 Net carb per slice. Some fruits are relatively low carb, such as berries (strawberries, blueberries, raspberries). Don’t by any low-fat dairy and you’ll be eating low-carb dairy foods. Legumes are a problem for they contain a lot of carbs and a lot of fiber; you just need to control the amount that you ingest.



Starchy foods, such as potatoes and rice, although they contain complex carbohydrates, they are still carbohydrates. Once absorbed, the complex carbohydrates in starchy foods are converted into glucose just like carbohydrates do, so they produce an insulin response when ingested. Remember you want to decrease the insulin secretion, so you get less fat deposition from the glucose into your fat cells.


4.Bad fats

The difference between bad fats and good fats is a bit controversial. Some people say you should avoid saturated fats, but coconut oil is a saturated fat and is healthy. One can see this in the Asian population in south-east Asia. They are very healthy, grow older than we in western societies, yet they consume a lot of coconuts and coconut oil.


Other examples of fats that were once thought to be bad but actually are not bad for you include cheese and butter. Even yogurt is not bad, as long as it is full-fat yogurt. Low fat yogurt actually contains more carbs to make up for them taking away the fat, which really messes up the equation. Generally, fermented milk products are better than just plain milk, but if you drink milk, try to use the whole fat one.


Bottom line these are “natural” saturated fat products and not man-made saturated fat products. For instance, margarine is a saturated fat, but man-made. The manufacturers synthetically make this by adding hydrogens to vegetable oil. Unfortunately, your body doesn’t exactly know what to do with this so these become a problem. These are the bad fats: those not natural, synthetically produced, and are essentially “foreign” to your body.


In addition, when you absorb some of these unnatural fats, they can produce an inflammatory reaction within your body because literally your body thinks they are not good. Your DNA is not equipped to utilize them well, so your body thinks it must fight-off these foreign invaders because they are so unnatural. This results in inflammation, and this inflammation is the root cause of degenerative processes that occur as we grow older. The rule is to decrease inflammation as much as possible to grow older, not the opposite.


  1. Fats cooked at high temperature


When heated, all fats have a certain temperature at which they “burn” or degrade. For instance, if you’ve cooked with olive oil you probably have noted that you can’t heat it up to high temperatures. If you do, it smokes (burns) and it makes the food not taste good. Don’t do that, it degrades the olive oil, so you don’t get the benefit from eating good virgin olive oil. Cook with it but at moderate temperatures.

On the other hand, many vegetable oils can reach high temperatures before they “burn”. Unfortunately, when you cook meats at high temperature, toxic substances can be produced which can cause inflammation and harm your body. Thus, we recommend you avoid most deep-fried foods for this reason. Sautéing your foods is generally okay.


Thus, the difference between a good fat and a bad fat really has a lot to do with the type of fat, where it is from, and the temperature used to heat the fat. Using natural fats is better than any man-made ones. Think about our ancestors the caveman when eating fats. If they had the fat in their surrounding and their diet, their DNA developed over the eons of years to be able to utilize the fat in a healthy manner. If the fat is of recent production, it is most likely foreign to your body, can cause inflammation, and should probably be avoided.




In summary, foods to avoid or limit on a ketogenic diet are foods with a lot of carbs. Foods with more fat content, but good fats, are the ones you should ingest to keep your body in ketosis, which actually is a healthier type of metabolism.