Most diets will promise rapid weight loss and other health benefits. That sounds great, but you want those claims supported by scientific evidence.
I am going to focus on the low carbohydrate approach.
The premise of low carb diets is that you will lose weight by restricting carbohydrates -like during starvation- and reducing insulin production. In a low carb environment, you will convert diet and stored fat into ketones which are energy carrying acids that can fuel most of our body. The burning of fat from deposits will lead to weight loss.
The high protein content of low carb diets increases the feeling of being full, which helps a person trying to reduce calories.
The Atkins diet is the most famous of the low carb diets. The Ketogenic (Keto) diet, is very similar to the Atkins diet in that both restrict carbohydrates to trigger ketosis. While the Atkins diet relaxes the restriction of carbs after the first few weeks, the Keto diet maintains the same proportion of macronutrients over time to ensure continued ketosis. Foods allowed in the Keto diet include meat, fish, eggs, butter, nuts, healthy oils, avocados, most green vegetables, tomatoes, onions, and peppers.
Does it have a scientific foundation?
Yes, the principle of restricting carbs to switch to ketones as fuel is scientifically sounded.
Can you keep up with it?
If an eating regimen impose serious restrictions, it will be very difficult to follow, right? It makes sense. A diet easy to follow is one that fits into your lifestyle and that of your family.
The Atkins diet which became very popular in the 90s has been replaced more recently by the Keto diet as the most popular low carb diet in the US. We are being bombarded by many keto books, recipes and supplements. The Keto diet is extremely restricted, and therefore difficult to follow. It is hard to imagine long term adherence.
Will it help you maintain the weight over time?
If you are looking for a long-term solution, the keto approach is not for you. Quick weight loss diets like the keto diet usually emphasize some drastic cut in nutrients or the elimination of an entire food group that can't be maintained over time. When the diet stops, the weight comes back, often at higher levels than at the start of the diet.
Will it be healthy in the long term?
This is very important. Many diets propose a macronutrient composition with unknown long-term effects. In the Keto diet, reliance on fats makes us question its long-term effects on our health.
What do the experts say in 2020?
In the U.S. News & World Report annual rankings, the keto diet came in next to last in the ranking of the best 35 diets.
But there may still be a role for this diet as it tied for third place in the race for best “fast” weight loss diet. It may be the diet for you if you have a wedding in 2-3 months and want to get into that dress or suit you like so much, but I would not recommend it if you are looking for long lasting weight loss and health benefits.
In summary:
The main pro of the keto diet is that it works short term for weight loss because the body burns fat efficiently. It could be used to lose weight fast for an event, like a wedding. The main cons are the lack of research into long term effects and difficulty to adhere to, since just one banana will put you over your daily carb limit!