Here it is in a nutshell:

Knowing the best diet to lose weight quickly is easy once you understand the basic principles of metabolism and insulin response. The hard part is knowing whether this promotes a long and healthy life. After all, promoting longevity through diet is the objective of this site.

But this is not what nutritionists want to talk about today. Everyone wants to talk about quick weight loss.

So what’s the bottom line? read on:

what's the best way to lose weight fast

What is the best diet to lose weight quickly?

The answer is to keep your insulin levels low.

When you look closely at the chain reaction at the molecular level in metabolic processes, the causality of weight gain is reversed. It is not that your cells store fatty acids because you are eating too much fat. It is that elevated insulin levels inhibit fat oxidation and further promote formation of fat from excess glucose. This metabolic process is known as lipogenesis (pyruvate -> acetyl CoA -> fatty acids), and it starts with an insulin spike.

No, you don’t need to be a doctor or biochemist to understand this. The simple fact is that insulin does not spike from ingesting fat. It spikes from ingesting carbohydrates. The more refined the carbohydrates, the higher the insulin levels spike. The higher the insulin levels, the higher the rate of fat absorption will be.

This simply means that the best way to lose weight quickly is to minimize those insulin spikes. Take control of the signaling mechanism that makes your fat cells to mop up glucose and fatty acids, and this is done by lowering carbohydrate intake. Diets that adhere to this principle are variations of the following:

  • Low carb diet
  • Low carb high fat diet
  • Ketogenic diet (or nutritional ketosis)
  • Paleo diet, which works to a lesser degree because it restricts refined carbohydrates

what is the best diet to lose weight fast

What is the best diet to lose weight and stay healthy?

Diets aiming to lose weight quickly are not usually the healthiest, but here’s the kicker:

Much to the dismay of the current nutritional and medical establishment, the evidence is increasingly suggesting that a diet substituting carbohydrates with fats as the primary energy source is actually beneficial. Even dietary cholesterol, the bogeyman of fat, turned out to be good for us after all according to the latest research.

Lower carb intake over time leads to reduced triglycerides, less LDL particle count and increase in HDL. Insulin sensitivity will improve and the brain’s ability to recognize leptin – the hunger hormone – is no longer impaired as it was under a high carb diet. Less glucose and more ketones as fuel means less glycation. Many of the byproducts causing oxidative stress – and thereby accelerating aging – are reduced.

The key is to never mix the fat with any amount of carbs sufficient to cause an insulin spike. In the presence of excess blood glucose, fat is also absorbed. To maximize the benefit and reduce oxidative stress even further, increase the ratio of omega-3 to omega-6 fat intake.

So what’s the catch?

There are, of course, caveats and nuances. For starters, genetics and epigenetics play a big role. Some gene groups predispose some of us to be less tolerant of alcohol. Others make some of us lactose intolerant. In our example of nutritional ketosis, there may be some subgroups of the population that cannot tolerate the diet for some reason or another.

For example, the group of genes known as the human-specific haplotype (Haplotype D) determine the conversion rate of omega-3 and omega-6 fats from vegetable sources. These processes of fat conversions produce the beneficial DHA and EPA, but they also produce a biproduct that causes inflammation: arachidonic acid.

Haplotype D carriers are far more efficient at converting omega-6 fats to arachidonic acid, which leads to inflammation and coronary artery disease. Therefore, Haplotype D carriers should increase omega-3 consumption at the expense of omega-6 if they want to avoid the negative side effects of the ketogenic diet.

Here are other known side effects:

  • Side Effect: You get dizziness and fatigue.
  • Solution: These are normal symptoms of adaptation until the body gets used to burning fat as a primary energy source. Supplement with magnesium, sodium chloride and lots of water to replenish the salts secreted by your kidneys when in ketosis.
  • Side Effect: The transition from glycolysis (aerobic metabolism of glucose) to lipolysis (aerobic metabolism of fat) is difficult for some people, with varying degrees of tolerance.
  • Solution: This process becomes more efficient with time, but you can always accelerate it by helping your body get rid of the remaining glycogen stores (do some aerobic exercise). Coconut oil also helps because it contains Medium Chain Triglycerides (MCT), which cannot be absorbed by the body and must be digested. The immediate breakdown of MCT accelerates the body’s shift to lipolysis. You can also supplement with caffeine, which speeds up fat mobilization by upregulation of hormone sensitive lipase (HSL).
  • Side Effect: You are perceived as being anti-social. Humanity’s food system today was built on agriculture that brought us high carbohydrate food. Friends may not be understanding in a dinner party.
  • Solution: Restaurants are starting to accommodate the eccentric requests of the low-carb crowd. Friends will eventually come to understand your needs. If you were diabetic, people accommodating your diet would not be an issue.
  • Side Effect: If you are diabetic, there is a risk of ketoacidosis.
  • Solution: It is still possible to be in nutritional ketosis, but any such diet plan has to be monitored by a medical professional. The reason is that insulin also regulates ketone production, and in healthy humans insulin works to cap ketones at a level for which they are adapted. This can be a problem for type 1 diabetics who produce no insulin and type 2 diabetics who have become so resistant to insulin that liver cells do not get the signal to turn off ketone production.


But of all the arguments against the diet, the idea that dietary fat is what initiates weight gain does not match up with the scientific evidence at our disposal today. Unutilized fat in the gut is excreted through the normal digestive process.

counting calories

The “Calories In, Calories Out” Fallacy

The first law of thermodynamics is often invoked to attack low carb high fat diets because many of their adherents argue that your body can take in more calories. Critics say that to increase calorie intake and lose weight is an incoherent fantasy, but the real fantasy is using ingested calories as a proxy for the actual utilization of the cellular fat storage buffer.

The problem with reducing every macronutrient into its equivalent energy yield in kilocalories is that it fails to take into account the metabolic pathways each nutrient takes. Coal, for example, has carbon atoms, and its energy output can be quantified in calories. But that does not mean that humans can digest coal or produce ATP energy from it.

In the same way that coal requires different machinery to extract its energy, each macronutrient utilizes a different metabolic pathway in humans.

At the molecular level, the energy required to metabolize each macronutrient is different, and different pathways produce different byproducts.

At the human body level, byproducts and unmetabolized energy is excreted all the time through fecal matter, urine, methane, heat and respiration. So if the first law of thermodynamics is to be applied, the closed system must include the environment with which energy sources are exchanged.

Evolution of High Carb Low Nutrient Corn

Historical Context

For detractors, it is worth noting that refining carbohydrates is a recent introduction into the human race. From an evolutionary perspective, it does not count much at all as an anchor to what is a “normal” diet for homo sapiens.

To put it in perspective, cooking has been around for 200,000 years and refined carbohydrates for only 1 century. With most non-western populations only recently introduced to this western diet, the real question is whether humanity had sufficient time to genetically adapt to such a dramatic change in macronutrient composition.

There has never been a time the history of homo sapiens where there has been such an abundance of low quality food. Mankind survived the last ice age on very little but nutrient-rich food. Our bodies are built to withstand long periods of famine, and there is much evidence that fasting is in fact beneficial to health and longevity.


So, if you must lose weight quickly, then the ketogenic diet is probably your best option without doing harm to your body. You just need to remind your body how to metabolize fat again.

To be specific, switch your macronutrients to 60-70% fats (prioritize saturated, monounsaturated and omega-3 fats) and keep carbs at 5-10%. Minimize protein to prevent an insulin spike. You really need very little protein, even if you are into vigorous and frequent exercise, but you can experiment and see what gets you in and out of ketosis.

As always, please inform your doctor or medical care professional before undergoing this diet. It is not for everyone.


Genetic Adaptation of Fatty-Acid Metabolism: A Human-Specific Haplotype Increasing the Biosynthesis of Long-Chain Omega-3 and Omega-6 Fatty Acids (Am J Hum Genet. 2012 May 4; 90(5): 809-820).

Gibbs BF, Goncalves Silva I, Prokhorov A, Abooali M, Yasinska IM, Casely-Hayford MA, et al. Caffeine affects the biological responses of human hematopoietic cells of myeloid lineage via downregulation of the mTOR pathway and xanthine oxidase activity. Oncotarget. 2015;6(30):28678–92.

Taubes, Gary. 2009. The Diet Delusion [Kindle version].

Taubes, Gary, 2011. Why We Get Fat: And What to Do About It [Kindle version].