Keto Diet: pros & cons

Published on: 03/18/2021

I continually get asked about the Keto diet and what are my thoughts on it. Some people continue to think that the keto diet is a high protein/high meat diet. Adkins diet restricted carbohydrates while eating fat and protein. Then paleo came along restricting certain carbohydrate like grains and legumes. Keto diet is actually a lower protein diet, low carbohydrate & fiber, and high fat diet.

  • 50g carbohydrates or less a day which causes the liver to produce ketones as a side effect so that the body can preserve glucose (blood sugar).
  • Protein is low to moderate to help preserve ketosis. If eating too much meat, then the body will be kicked out of ketosis.
  • Of calories, 70-80% is fat, 5-10% carbohydrate, and 10-20% protein

Most people I talk to who ask me about the diet usually know someone doing the keto diet and they lost, so they think it’s good for them too. However, most of them are not doing a real keto diet but just a low-carb diet. Keto involves checking to see if you are in ketosis by checking your urine. Ketosis happens after 3-4 days when the body is deprived of glucose for fuel and the body has no other choice except to switch to using fat for fuel.


The Keto diet has been around since the 1920s which it was used to treat refractory epilepsy in children. Most seizures in epilepsy can be controlled by medication, however, some continue to have seizures and a ketogenic diet may help them. So, the keto diet was originally intended for those with epilepsy to treat seizures. Getting specific on diet parameters for epilepsy and ketogenic diet will have to be a whole other blog post (let me know if you want that).

There is now ongoing research with cancer, multiple sclerosis, Alzheimer’s, and diabetes.


These are just a few of the current research articles I found when searching on Pubmed.


Like I mentioned there is growing research regarding type 2 diabetes. One study showed that people either were on low carbohydrate keto diet or low glycemic in those with type 2 diabetes [1].

  • <20g carbohydrates a day with no calorie restriction or low glycemic index eating 55% calories from carbohydrates with reduction in overall calories by 500 from their normal intake.
  • After 24 weeks, there was a reduction in A1c which was greater in ketogenic diet
  • 20 of 21 participants had eliminated or reduced medication vs. 18 of 29 in low glycemic group.

In 2017, an online intervention looked at low carbohydrate/keto vs. standard plate for diabetes [2].

  • the very low-carbohydrate ketogenic diet, to reduce carbohydrate intake to between 20-50 grams of non-fiber carbohydrates a day to get into ketosis. They also received some cognitive behavior training such as Mindfulness-Based Eating, along with encouraging participants to increase physical activity and sleep.
  • diet program based around a plate method diet, the American Diabetes Associations’ “Create Your Plate” diet, a low-fat diet that emphasizes green vegetables, lean protein sources, and somewhat limited starchy and sweet foods. One big downside to this study is this plate group did not receive the extra behavior training or encouragement to increase physical activity and sleep.
  • So, after looking at the parameters it makes sense that the “Individuals with type 2 diabetes improved their glycemic control and lost more weight after being randomized to a very low-carbohydrate ketogenic diet” because the keto diet had additional support that the group in the plate for diabetes did not.

In 2016, 89 men & women with type 2 diabetes for 4 months went on either very low-calorie-ketogenic diet or low calorie diet [3].

  • goodness this was very low calorie of 600–800 calories per day, low in carbohydrates (<50 g daily from vegetables) and fat (only 10 g of olive oil per day), 0.8 and 1.2 g per each Kg of ideal body weight. PLUS “supplements of vitamins and minerals, such as K, Na, Mg, Ca and omega-3 fatty acids, were provided in accordance with international recommendations. This active stage is maintained until the patient loses most of weight loss target, ideally 90%”.
  • Low-Calorie diet: 500–1000 calories based on each individual’s basal metabolic rate. <30% of calories coming from fat, 10–20% from protein and 45–60% from carbohydrates.
  • A very low-calorie-ketogenic diet is most effective in reducing body weight >10% loss from starting weight, and improvement of glucose control in this study vs. low-calorie diet.  However, insulin sensitivity was lower in the low-calorie group. Insulin sensitivity is how well the cell responds to insulin. Those who do not have diabetes or blood sugar problems are insulin sensitive, so if you are diabetic it’s a state you want to get back to.

A meta-anylisis in 2020 looked at overweight and obese with type 2 diabetes. A ketogenic diet was more effective in improving weight control, glucose, and cholesterol numbers in patients with overweight or obesity, especially those with preexisting type 2 diabetes, as compared to low-fat diets [4].


In 2013, British Journal of Nutrition did a meta-analysis on long-term (12 months) weight loss of ketogenic diet vs. low fat diet [5].

  • ketogenic diet <50g carbohydrates vs. low-fat diet of <30% of calories from fat
  • The ketogenic diet showed more weight loss, decreased body weight, Triglycerides, and blood pressure while increased HDL-C and LDL-C.

A more recent study in 2020, a comparison between the ketogenic diet and low glycemic[6]. The participants were obese without any health conditions.

  • both diets consisted of 1600 calories a day over 18 months.
  • Keto parameters “≤35 g of carbohydrates per day, and ≤ 10% of total calories were from saturated fats. Daily protein intake was set at 1.2 g/kg body weight for females, and 1.5 g/kg body weight for males”
  •  The low glycemic group got analyzed for sensitivity to carbohydrates, so the baseline was “refined carbohydrate content (maximum 10, 8%, or 6% total calories) and saturated fat content (maximum 10, 8%, or 6% total calories)”
  • The participants were asked to exercise for 30–45 min per day, 5 days per week
  • keto group had to measure ketones daily. There was less adherence in the keto group to the diet compared to the low glycemic group.
  • similar weight loss at 6 and 12 weeks while at 24 weeks the ketogenic group had lost more weight.  The ketogenic diet was associated with a 17.2% loss in body mass at 18-month and low glycemic at 25.3%. At 2 years, the low glycemic continued to low weight while low ketogenic regained some weight. Also, long-term the low glycemic group had better cholesterol, HDL, and glucose numbers.


  • mental clarity
  • consistent energy
  • weight loss
  • reduced appetite
  • improvement in blood sugar as stated above


  • sustainability
  • keto flu: electrolyte imbalances due to loss of fluids. Increased need for salt, potassium, and magnesium
  • gallbladder issues such as stones
  • kidney stones
  • reflux
  • nutrient deficiency
  • constipation
  • sleep disturbance
  • adherence
  • increase risk for decreasing longevity of life


There is very little specific research on keto and mortality, but there is several on low carb diet [7].

In the European Heart Journal in 2019, looked at all-cause mortality and low carbohydrate diets from the National Health and Nutrition Examination Survey (NHANES; 1999-2010).

  • “lowest carbohydrates intake (quartile 4 of LCD) had the highest risk of overall (32%), cardiovascular disease (CVD) (50%), cerebrovascular (51%), and cancer (36%) mortality.”
  • “The association between LCD and overall mortality was stronger in the non-obese (48%) than in the obese (19%) participants.”

In 2018, in the Lancet a meta-analysis was conducted including overweight patients from 21 different countries with between 7 and 26 years of follow-up. [8].

  • Showed the lowest mortality with mid-range carbohydrate dietary consumption at 50% to 55% of total daily energy consumption, compared with a low-carbohydrate diet (< 40% of total daily energy intake) or a high-carbohydrate diet (> 60% of total daily energy intake).
  • Interesting that “in a low-carbohydrate diet, if energy from carbohydrates was replaced with animal-based protein (lamb, beef, pork, and chicken) or fat sources, it was associated with increased mortality, compared with decreased mortality if the energy was replaced with plant-based protein (vegetables, nuts, peanut butter, and whole-grain bread).”

In 2013, Low-carbohydrate diets and all-cause mortality: a systematic review and meta-analysis [9].

  • low carbohydrate diets showed 30% increase in all-cause mortality. so it did not matter what the cause was of death people who ate a low carbohydrate diet were 30% more likely to die than those who did not.


If at this point you are still wanting to move forward with ketogenic diet, I would suggest doing a Plant-based version including fish, tofu, tempeh, a variety of colorful non-starchy vegetables, berries, nuts/seeds, avocados, olives, and coconut. This way you would focus on healthier plant-based sources of fats while obtaining a variety of nutrition from those plants too. This plan would be more of a mild ketosis depending on total carbohydrate intake. 65% fat, 20% protein, and 15% carbohydrate.



  • olives
  • coconut
  • avocado
  • nuts, seeds, nut butters
  • oils
  • plant-based butter
  • coconut cream


  • vegetables: artichoke, arugula, asparagus, ambo shoots, beets, bok choy, broccoflower, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, celeriac root, celery chard/Swiss chard, chervil, Chinese cabbage, chives, cilantro, cucumbers, daikon radishes, eggplant, endive, escarole, fennel, fermented veggies, garlic, green beans, greens: beet, collard, dandelion, lake, mustard, turnip, etc; horseradish, jicama, kohlrabi, leeks, microgreens, mushrooms, okra, onions, parsley, peppers, radicchio, radishes, salsa, scallions, sea vegetables, shallots, snap peas/snow peas, spinach, squash: delicata, spaghetti, yellow, zucchini; tomato, , water chestnuts, watercress
  • fruit: berries, lemon, lime, avocado


  • fish
  • tofu
  • tempeh
  • egg

Have a Happy Healthy Day!


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Angela Peralta RDN, LD is the founder of Dietitian Angela LLC and creator of the Digestive Research Library. She has a bachelor of science in Nutrition and Food Science from Georgia Southern University, is a Registered Dietitian Nutritionist since 2007, and has a Certificate of training in Integrative and Functional Nutrition from the Academy of Nutrition and Dietetics.

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