Vegetarianism (also known as veganism) is a philosophy and/or a way of life that excludes the use of animals or animal products for food, clothing or other purposes. In practice, a strictly vegetarian (vegan) is committed to avoiding consumption of all animal products (meat, fish, chicken, honey, eggs and dairy products) and using products from animal sources.
Vegan diets have enjoyed a rise in popularity in the last years, especially with the help of newer books, studies showing an improvement in health, vegan websites and hundreds of videos on Youtube.
As a result, many people want to be vegans, either because they want to improve their health, or because they want to lose weight. However, I don't think that going vegan is the key to have a better health.
First, a diet that requires supplements , is not the best choice out there. Vegans are at a high risk for cobalamin (Vitamin B12 ) and calcium deficiency and an increased risk for inadequate levels vitamin D and iodine [4, 5, 6], unless proper food planning including supplements and/or fortified foods are utilized.
Furthermore, taking vitamin B6 and B12 supplements appear to cause cancer in men .
Let's see for example this study , where they studied the impact of vegan diet on health and growth of children and adolescents.
They found that a vegan diet can be adequate during childhood and adolescence and while growth of vegan children is within a normal range, they were lighter and slightly smaller than omnivores.
By avoiding eggs, liver, kidneys, and seafood, foods which are naturally rich in cholesterol, the master chemical when it comes to producing hormones, you can experience unwanted side effects related to hormone imbalances, especially from hormones that cholesterol is needed to make them, like Pregnenolone , DHEA, and testosterone .
When you have adequate levels of cholesterol in the blood, your cells can break it down and use its constituent parts to make pregnenolone. Pregnenolone is a neurosteroid  and steroid hormone precursor , that is, it both acts in the Brain to exert steroid-like effects  regulating mood  and stimulating cognition .
Pregnenolone deficiency can cause numerous problems, including :
- Fatigue/low energy 
- Sense of being unwell 
- Increased susceptibility to stress and decreased adaptation 
- Loss of alertness 
- Poor memory/brain fog 
- Other Hormone imbalance 
- Sexual dysfunction/low libido 
- Thyroid abnormalities 
- Low levels of sex hormones 
The same goes and for testosterone, where vegetarians have significantly lower testosterone levels than meat eaters .
Now let's look on another thing. Let's take vegans for example. They are lean, aren't they? Vegans claim that the meat is the main factor for diabetes, insulin resistance and more. However, many vegans can't lose weight at all .
Now, let's take the keto people, that is the people who are on a ketogenic diet. These are lean too, but some of them can't lose weight either . But the most people saying that going low-carb, helped them to lose weight, reduce LDL and triglycerides, reduce their blood pressure and they feel amazing.
So, if the low-carb diet can help you lose weight and be healthy, but some people struggling to lose weight, and on the other hand, many people can lose weight with a high carb diet, and in here, some of them can't lose even a pound. Then why to choose one diet over the other? Why to avoid carbs or meat, when the problem is clearly not them and you can enjoy both?
So what's the connection here? If the vegans can lose weight and the ketogenic diet can help you lose weight too, then why so many people can't lose weight on a vegan diet? Or, why to go on a vegan diet, if so many people lose weight on a keto diet, while so many vegans can't lose weight? If the meat is the problem here, then why so many vegans still having problems with their weight? thus, in this study , 10 Days of 'Paleo Life' will strip up to 18 cm off your waist and boost your insulin sensitivity by 53%.
The answer is the food choice. The quality of the food you eat has more value than the type of diet you are on. This is the connection on every diet out there, either you avoiding carbs, fat, meat or anything else, you are also avoiding the foods that are full of vegetable oils and processed carbs. That's the reason why most vegans can't lose weight.
Many people are going vegan because they thing that those products are healthier. Well, this is true in most cases but many vegans buying foods that are unhealthier than animal products, they are full of vegetable oils and sugar. This is the same and on keto guys, they buy products "keto" friendly, while those products are full of vegetable oils, the main cause of weight gain .
Take for example the Earth Balance's faux butter , which is advertised as a natural product aimed at vegans. Look at its ingredients. It contains:
Palm fruit oil, canola oil, soybean oil, flax oil, sunflower lecithin, lactic acid, and 'natural flavor'.
Do you think that this 'natural' product is healthier than butter, which only contains fat, milk proteins, and water? Well think again, because those vegetable oils are the worst thing you can eat .
Or take a look at the peanut butter or the almond butter, the best choice of fat for vegans. Peanut butter contains no omega-3s, but it's full of omega-6s. The same goes and with almond butter . Researchers have associated excessive omega-6 fatty acids with inflammation and an increased risk of cardiovascular disease . So, eating a lot of peanut/almond butter, believing that they are healthy, is wrong. On the other hand, grass-fed animal products have more omega-3s . So, what's healthier ?
Eating a lot of meat and especially processed meat is not the best choice either. Eating processed meat — including hot dogs and bacon — does increase the risk of colorectal cancer, according to a review of the available research by WHO .
But on the other hand, beans, grains, cereals and some vegetables and fruits contain lectins [30, 31], a type of protein that can cause damage to the lining of your gastrointestinal tract or your organs and interfere with metabolism when consumed in large amounts. Rice contains arsenic , a toxic chemical.
Plants also having phytic acid, a unique natural substance found in plant seeds . Phytic acid impairs absorption of iron and zinc, and to a lesser extent calcium [34, 35]. In normal quantities phytic acid may have antioxidant  and anticancer properties , 38], but if you are a vegan, you have to consume a lot of those foods, in order to reach your caloric needs.
And according to this study , adults who consume a vegetarian diet are less healthy (in terms of cancer, allergies, and mental health disorders), have a lower quality of life, and also require more medical treatment.
Remember, by avoiding processed food, you are avoiding the processed oils and the processed grains that cause many health problems. Is not the vegan or the paleo or the ketogenic diet that helps you lose weight and be healthy, it's the avoidance of so many processed stuff and the toxins they have. That's why vegans can't lose weight if they are keep eating crap, because it's the processed stuff the problem.
I believe that a well balanced diet is the best diet for you to try. Avoid processed meat and always choose animal products from grass fed animals. Most animal products, like milk, contains hormones that maybe has an impact to our health  (well, that's controversial ), so choose wisely. But don't go wild with milk consumption, as the Ethiopian tribesmen compete to get as fat as possible by drinking cow milk .
Avoid anything that is cooked with vegetable oil or anything contains vegetable oils (like most super market items). Eat your steak with a salad, but not with french fries. Drink your milk with a banana or instant oats but not with cookies (unless you made them and you know what's in there).
Consume dairy full in fat and avoid anything low in fat, because low-fat dairy intake may raise Parkinson's risk .
See the Hadza tribe  for example. Hadza is our last remaining link to the diets on which humans evolved and through which our digestive system developed. Hadza, because of their diet, have the most diverse human gut microbiomes on the planet. They are eating beans (from baobab trees), fruits and meat.
Reading about the Hadza tribe, or about the Tsimané , with a diet high carbohydrate diet of rice, plantain, manioc and corn, and a small amount of wild game and fish, came to my mind the Ori Hofmekler's 'Warrior Diet'. Maybe this is the proper way of eating.
Last, I have to mention a new documentary that is out on Netflix ant it seems to have a lot of people talking about going vegan, the 'What the Health' . What the Health is a vegan-promoting documentary, but before decide going vegan or not, based on that documentary alone, you should read some Debunking articles about it [45, 46].