Fat Burners: The Doctor’s point of view
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Continuing with the topic of dietary supplements, I will start by talking about the famous fat burners. These supplements are frequently requested by people who want to decrease their percentage of abdominal fat, and are promoted by some fitness trainers and gyms. For this reason, I want to give my personal point of view about them.
These are the most used:
Caffeine
Caffeine is a common ingredient of Sports supplements because it may modulate central fatigue, decrease ratings of perceived exertion and pain, and improving levels of vigor.
Recommended Dose
3–6 mg/kg/body weight, less than 60 minutes before exercise and if practical, during exercise.
It is also advisable to suspend its use at 7-day intervals to prevent the receptors where caffeine works from decreasing and therefore improve its effect.
Effectiveness
There are short term clinical trials of combination product whose main goal is weight loss. It has inconclusive effects on weight loss.
However, there is good evidence for improved endurance capacity, increasing time to fatigue and time trial activities from 5 to 150 minutes’ duration across a wide range of exercises. Caffeine has also been shown effective to short duration high-intensity exercise, improving performance time, mean speed and power, and peak power in a cycling time trial of 1 to 2 minutes’ duration.
Adverse effects
Anxiety, insomnia, restlessness, nausea, arrhythmias, hypertension, tremor, head- ache, diarrhea
Do I recommend it?
Yes.
Green Tea Products
Green tea is produced from the leaves of Camellia sinensis L., and it is highly consumed globally, as it is recognized as one of the most popular beverages. Also it has potent antioxidants, and anti-angiogenic effects in vivo and anti-proliferative effects in vitro in cancer.
Green tea is part of the concept of functional food which was introduced in the 1980s first in Japan due to health care costs.
Effectiveness
There are several clinical trials of good methodological quality nevertheless, a recent systematic review (2020) did not confirm the anti-obesity effects of the green tea products in nondiabetic overweight and obese females. It seems that green tea has possible modest effect on body weight.
Adverse effects
The most feared is liver damage, which there is clear evidence about the occurrence of liver damage from the ingestion of green tea in humans albeit with very low frequency and further suggests that specific green tea constituents, particularly Epigallocatechin gallate and other catechins found in this supplement. The factors that can contribute to this adverse effect are the concentration of catechins in certain green tea containing products, the bolus dose provided by certain dosage forms such as capsules and tablets, and the intake of green tea under fasting conditions which increases the absorption of its constituents which has been observed in clinical and animal studies. So far there is no evidence in humans that there is a clear relationship with the dose.
Others side effects are constipation, abdominal discomfort, nausea, and increased blood preassure.
Do I recommend it?
No.
L- Carnitine
L-carnitine is a vitamin-like substance and a non-protein modified amino acid, which is mainly produced in the liver and kidney and vitamin C, iron ions, and niacin play role in its production The main dietary sources of L-carnitine are meat, fish and some other animal products such as milk. This substance plays a major role in the fat metabolism.
Effectiveness
There are several clinical trials with weight loss as a secondary outcome. It reduces body weight, BMI and fat mass, mainly in adults with overweight/obesity than those with normal BMI range.
L-carnitine supplementation results in 1.53 Kg and 1.29 Kg weight loss in people with overweight and obesity, respectively. The reducing effect of L-carnitine on body weight was 1.08 kg in studies with follow-up period of 12 weeks and 1.48 kg in studies with follow-up period of >12 weeks.
According to Nasir Talenezhad (clinical nutritionist) and his collaborators it seems that consuming healthy dietary patterns for weight loss is more logical compared with L-carnitine supplement. Because the same and even more weight reduction can be achieved by following healthy diets like Mediterranean, dietary approaches to stop hypertension (DASH), vegetarian, low-fat, and low-carbohydrate diets without considering the energy intake.
Safety
No safety concerns reported for up to 2 gr/day for 1 year or 4 g/day for 56 days.
Adverse effects
Nausea, vomiting, diarrhea, abdominal cramps and “fishy” body odor. It may increase cardiovascular disease risk in some patients
Do I recommend it?
Maybe I would.
Conjugated linoleic acid (CLA)
Conjugated linoleic acid refers to a type of fat. Dairy products and beef are the major sources of conjugated linoleic acid in the diet. An average diet supplies 15–174 mg of conjugated linoleic acid daily. CLA increases lipolysis, reduces fat production and promotes programmed death of adipose cells.
Effectiveness
Conjugated linoleic acid is commonly taken by mouth for weight loss. It is also often used for bodybuilding and fitness, but there is limited scientific evidence to support these uses. It has a minimal effect on body weight and body fat. Studies on the body fat lowering effects of CLA in humans have produced variable results
In general, the effects of CLA on humans have been much smaller than those observed in animals. The effective dose for CLA in animals and humans is still unclear.
Safety
No safety concerns reported for 2.4–6 g/day for up to 12 months.
Adverse effects
Abdominal discomfort and pain, constipation, diarrhea, loose stools, dyspepsia, and adverse effects on blood lipids and sugar levels.
Do I recommend it?
No.
7- Keto DHEA
7-keto-DHEA is formed from dehydroepiandrosterone (DHEA) in the body. DHEA is a “parent hormone” produced by adrenal glands. But unlike DHEA, 7-keto-DHEA is not converted to steroid hormones such as androgen and estrogen.
People take 7-keto-DHEA to speed up metabolism and heat production, which can promote weight loss. 7-keto-DHEA is also used to improve lean body mass and build muscle, increase the activity of the thyroid gland, boost the immune system, enhance memory, and slow aging. It is also used to treat depression, anxiety, and post-traumatic stress disorder.
7-keto-DHEA might promote weight loss by speeding up the body’s metabolism and converting more energy to heat instead of storing it as fat.
Effectiveness
There is lack of evidence about promoting weight loss, improving lean body mass, or building muscle. DHEA and androstenedione share many endocrine-metabolic pathways with different anabolic steroids and androgens (eg, testosterone), and they also share the same adverse effects and risks to health. Consequently, owing to different ethical and endocrinological concerns, their nontherapeutic use in healthy individ-uals (athletes and non-athletes) is not advised, especially in young people.
Do I recommend it?
No.
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