Why Low Fat Diet Is The Least Effective in Long Term, Says Harvard
If you want to lose weight and keep it off, a Harvard study says low-fat diet is not the most effective diet. Here are the reasons.
The study, published in The Lancet (Oct 2015) compares randomized controlled trials (RTCs) on low-fat, low-carb and high fat diets. They found that compared with other dietary interventions of similar intensity, evidence from RCTs does not support low-fat diets over other diets for long-term weight loss.
Why don’t low-fat diets work?
Low-fat diets encourage eating harmful foods. When the low-fat craze began in the 1970’s foods were developed that were low-fat but high sugar, or had other ingredients that aren’t good for you. I suggest reading labels and eating real foods not foods that are processed.
People need fat for hormone and other body functions. One of the side effects of a low-fat diet is significantly reduced testosterone levels, one study showing a reduction of 12% after 8 weeks on a low-fat diet. Having low testosterone levels can lead to decreased muscle mass, increased body fat, osteoporosis, depression, decreased libido, among others. 
Cancer patients need more fat in their diets and fat may help prevent seizure activity. Dr. Thomas Cowan says that cancer cells love sugar but can’t metabolize ketones which are the byproduct of burning fat. He has successfully treated cancer patients and avoided a common side effect of cancer, extreme muscle wasting or cachexia by using a very high fat ketogenic diet. Cancer patients on a ketogenic diet will often have their tumors shrink and will halt their cachexia—their physical wasting and weight loss. The cancer cells starve on a ketogenic diet, but normal cells thrive. Likewise according to the Epilepsy Foundation, a high fat diet halts seizure activity in patients when medications are sometimes ineffective. 
Low-fat diets contribute to heart disease. It’s well documented that people in other countries like France and those who follow the Mediterranean diet which uses quality fats like olive oil, nut oils and avocados and eliminate processed oils like vegetable oil have less heart disease, diabetes and even cancer. When these people eat a Western diet they have the same risk and incidence of these diseases as Westerners.  Vegetable oils are known to cause inflammation and heart disease. . Low fat diets contribute to higher cholesterol levels, lower HDL your beneficial lipoproteins and higher LDL the dangerous lipoprotein which Dr. Atkins documented in his book The New Diet Revolution and Drs. Michael and Mary Dan Eades expound on in their book Protein Power.
So, the key to long-lasting weight loss is to eat clean and lean.
Do include meat but keep it to a piece the size of your palm. Naturally fed meat is an excellent source of Omega-3 fatty acids, CLA, vitamins and minerals along with important nutrients like Carnosine and Creatine.
Eggs are among the healthiest foods on the planet. They are loaded with vitamins and minerals, along with Choline and powerful antioxidants that protect the eyes.
Grass-fed dairy products are the best source of Vitamin K2 in the diet. Also loaded with Calcium, CLA and plenty of other nutrients.
Coconut products contain fats that are associated with powerful health benefits, including increased fat burning, better blood lipids and improved brain function.
Nutrient dense fruits and vegetables such as berries that contain ellagic acid and vegetables like spinach, kale and bell peppers are rich in antioxidants and other plant phenols.
The bottom line is we need fat in our diet for all of our cells to function and for metabolism and chemical reactions. The key is to eat healthy fats and eliminate sugar, flour and processed foods.