Last week I talked about the explosion of individuals selling fake HGH creams and gels.
Read about it here:
Another thing I've seen dramatic rise in, is the number of people adopting a ketogenic diet for weight loss.
So I want to use this week's post to breakdown what the ketogenic diet is, the good, the bad, and the ugly or beautiful.
Then you can make an informed decision based on balanced information, not propaganda given by individuals that want you to buy their Keto products.
Obesity is Still the Question, Is Ketogenic Eating the Answer?
Obesity is reaching epidemic proportions and is a strong risk factor for a number of cardiovascular and metabolic disorders such as hypertension, type 2 diabetes, dyslipidemia, atherosclerosis, and also certain types of cancers.
Despite the constant recommendations of health care organizations regarding the importance of weight control, this goal often fails.
Genetic predisposition in combination with inactive lifestyles and high caloric intake leads to excessive weight gain.
Even though there may be agreement about the concept that lifestyle changes affecting dietary habits and physical activity are essential to promote weight loss and weight control, the ideal amount and type of exercise and also the ideal diet are still under debate.
For many years, nutritional intervention studies have been focused on reducing dietary fat with little positive results over the long-term.
One of the most studied strategies in the recent years for weight loss is the ketogenic diet.
Many studies have shown that this kind of nutritional approach has a solid physiological and biochemical basis and is able to induce effective weight loss along with improvement in several cardiovascular risk parameters.
Although some studies suggest that ketogenic diets show some promise in weight loss and general health, ketogenic diets are not without its risks and may not be ideal with individuals with pre-existing conditions.
But first, how do ketogenic diets work anyway?
The Physiology of Ketosis
After a few days of fasting or a drastically reduced carbohydrate diet (below 20 g per day), the body’s glucose reserves become insufficient for the production of oxaloacetate for normal fat oxidation and for the supply of glucose to the central nervous system (CNS) including the brain.
The CNS can not use fatty acids as an energy source (because they do not cross the blood-brain barrier), thus glucose is ordinarily the sole fuel for the human brain.
After 3–4 days of fasting or a very low carbohydrate diet the CNS needs an alternative energy source and this is derived from the overproduction of acetyl-CoA (an enzyme) which leads to the production of 3 so-called ketone bodies (KB):
β-hydroxybutyric acid (BHB)
This process is called ketogenesis and occurs principally in the liver (See Figure 1)
In the first days of a ketogenic diet the main source of glucose is from amino acids (AA), as the days goes by, the contribution of AA decreases whilst the amount of glucose derived from glycerol increases.
As a matter of fact glycerol can produce more than 16% of glucose in the liver during a KD and about 60% after a few days of complete fasting.
According to a study done by Bortz (1972) of the new glucose formed from protein and glycerol 38% is derived from glycerol in the lean and 79% in the obese.
During physiological ketosis ketonemia reaches maximum levels of 7/8 mmol/L with no change in pH while in uncontrolled diabetic ketoacidosis it can exceed 20 mmol/L with a concomitant lowering of blood pH (See Table 1)
Now that we have a good understanding about how Ketogenesis works, does it actually work for long term fat loss and is it safe for all individuals to use as a weight loss strategy?
Mechanisms of Ketogenic Diet Weight Loss Effects
There is no doubt that there is strong supportive evidence that the use of ketogenic diets in weight loss therapy is effective, however the mechanisms underlying the effects of KDs on weight loss is still a subject of debate.
Based on the available evidence, here are the top 4 mechanisms of KD weight loss effects:
Reduction in appetite due to higher satiety effect of proteins, effects on appetite control hormones and to a possible direct appetite suppressant action of the ketone bodies.
Reduction in lipogenesis and increased lipolysis.
Greater metabolic efficiency in consuming fats highlighted by the reduction in the resting respiratory quotient.
Increased metabolic costs of gluconeogenesis and the thermic effect of proteins.
Additional KD Advantages in Obesity
Researchers have argued that the ketogenic diet has beneficial effects other than simply fat and weight loss.
Davidson and colleagues recently suggested that ketones may protect from cognitive impairment caused by weight gain and obesity.
Moreover there is some evidence that ketogenic diets may have positive effects on mood in overweight subjects.
Even if during the very early phase of a ketogenic diet (the first 4 or 5 days) subjects may sometimes complain of lethargy this effect passes rapidly and subjects subsequently report an improved mood.
Also, the beneficial effects of KD in obese individuals are not just a function of weight loss per se but also improved glycemic control for obese individuals with insulin resistance.
A primary feature of insulin resistance is an impaired ability of muscle cells to take up circulating glucose and also the ability to slow down hepatic glucose output may be compromised.
Thus, individuals with insulin resistance have a fundamental problem metabolizing dietary carbohydrate and will divert a greater proportion of dietary carbohydrate to the liver where much of it is converted to fat (i.e., de novo lipogenesis), as opposed to being oxidized for energy in skeletal muscle.
When you dramatically decrease carbohyrdates in a ketogenic diet, there's little to no carbohyrdates to be converted into fat and you can possibly reverse the insulin resistance cycle.
Another beneficial effect that has been postulated for is related to longevity. Even though available data are restricted to animal models it has been shown that a ketone bodies ( β-hydroxybutyrate in particular) can act inhibitor certain types of tumor growth and treat several metabolic and neurological diseases.
Does KD Have a Rebound Effect?
While there are many studies which demonstrate that a ketogenic diet, at least in the short-term, results in greater weight loss than low-fat diets, from a long term perspective the success of a nutritional approach is defined by the amount of weight regain.
Some opponents and doubters of KDs suggest that any beneficial effects are only transient. There is no universally accepted definition of “successful weight loss maintenance” following a diet but a reasonable candidate would be that proposed by Wing and Hill in 2001, which defines it as “individuals who have intentionally lost at least 10% of their body weight and kept it off at least one year”.
The criterion of 10% is chosen for its well documented effects in the improvements in risk factors for diabetes and cardiovascular disease, while the 1-yr duration criterion was proposed in agreement with the U.S. Institute of Medicine (IOM).
It has recently demonstrated that two brief periods of ketogenic diet separated by longer periods of maintenance of Mediterranean diet (See Figure 2), led to successful long term weight loss and improvements in health risk factors without any weight regain.
We've addressed the mechanisms of KD weight loss, other health benefits, and its sustainability long term.
So the only question remains is: its safety for use as a weight loss strategy.
Does KD Possess Any Risk Factors?
Questions most often raised by colleagues when discussing KDs concern blood lipids.
In common opinion a low carbohydrate, high protein and fat diet is potentially unhealthy as it may cause a rise in LDL cholesterol and TGs and this issue is of special importance in obese individuals.
There are nevertheless several lines of evidence that point to beneficial effects of KDs on these cardiovascular risk factors.
The majority of recent studies seem to amply demonstrate that the reduction of carbohydrates can actually lead to significant benefits in total cholesterol reduction, increases in HDL and reduction of blood triglycerides.
Furthermore KDs have been reported to increase the size and volume of LDL-C particles which is considered to reduce cardiovascular disease risk since smaller LDL particles have a higher atherogenicity.
Another concern regards potential negative renal effects.
It is suggested that high levels of nitrogen excretion during protein metabolism can cause an increase in stress on the kidney and how they function.
In individuals with normal kidney function, higher dietary protein levels have caused some adaptations but without negative effects.
It is important though to take into account the renal related effects on blood pressure.
During ketogenesis, the amino acids involved in gluconeogenesis and/or production of urea have, in general, blood pressure lowering effects in healthy individuals.
On the other hand, Individuals with pre-existing kidney conditions, and even more so, those that are obese, will be more susceptible to the hypertensive effect of amino acids.
Noto and colleagues suggested a possible harmful effect of low carbohydrate/high protein diet (LC/HP) on health: i.e., an increase of all-cause mortality risk whilst there was no effect on CVD mortality.
On the other hand, for example, a large European study demonstrated that an increase in protein content and a reduction in the glycemic index led to better maintenance of weight loss without differences regarding adverse effects.
The existing contradictory evidences on this matter lies in the complex interactions between low-carbohydrate diets and long-term outcomes.
Moreover it is important to underline again that a ketogenic diet is not, strictly speaking, a LC/HP; KD is mainly a very low carbohydrate diet with a normal amount of protein that produce a peculiar metabolic state that should not be assimilated to a LC/HP.
It is reasonable to suppose that after a period of very low carbohydrate diet there would be an increased glucose sensitively and for this reason is advisable to have a transition phase from ketogenic diet to a normal diet.
In human subjects the effects of a very prolonged ketogenic diet are, as yet, not well investigated, for this reason, KD may be used safely for a limited period (from 3 weeks to some months) to stimulate fat loss, improve metabolism and help the transition to a well supported Mediterranean diet style eating strategy.
A period of low carbohydrate ketogenic diet may help to control hunger and may improve fat oxidative metabolism and therefore reduce body weight.
Furthermore new kinds of ketogenic diets using meals that mimic carbohydrate rich foods could improve the compliance to the diet .
Attention should be paid to patient’s renal function and to the transition phase from ketogenic diet to a normal diet that should be gradual and well controlled.
The duration of ketogenic diet may range from a minimum (to induce the physiological ketosis) of 2–3 weeks to a maximum (following a general precautionary principle) of many months (6–12 months).
Correctly understood the ketogenic diet can be a useful tool to treat obesity.
Until next time - ENVISION, BELIEVE, EXECUTE and SUCCEED
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