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FAT ATTACK NOV 22

Posted by: Unknown توقيت نشر: 18:10 / comment : 0 FAT ATTACK NOV 22, FAT ATTACK: FAT TRIMMING GH FRAGMNET APRIL 05, Fat Loss, life, loss, Rules Of Fat-Burning, slim

By Dan Gwartney, MD

Growth Hormone Secretagogues

A Tale of Two Pities

Growth hormone (GH) has long been considered the hormonal Fountain of Youth.¹ In addition to aiding in tissue repair and bioenergetics, GH also has potent anabolic and lipolytic properties that are of particular interest to bodybuilders and athletes.²

A Widening Interest

GH use by healthy adults is limited due to legal restrictions and cost. Physicians are increasingly being prosecuted or professionally ostracized for treating age-related decline of GH. Prescribing GH to a healthy, young adult for the purposes of improving appearance or athletic performance is prohibited, subjecting physicians who violate this edict to a loss of his/her medical license and potential imprisonment.³ No athlete has yet been banned from a sport or lost endorsements because of GH, as no legally defensible test for the hormone currently exists, though the World Anti-Doping Agency (WADA) claims they are near to having an algorithm developed that can detect GH use.

Many companies have touted products that claim to increase GH by stimulating natural GH production and release. The limitation to circulating GH isn't production, as the body has stores of GH in the pituitary well in excess of what's released. Instead, an interactive network of releasing hormones, inhibitors and secretagogues regulate the endocrinological balance to prevent GH excess or deficit in healthy people.⁴ Athletes have learned that increasing GH levels through daily or near-daily injections promotes tissue healing, reduces body fat and may increase muscle mass. The elderly also have a strong interest in GH, as natural levels steadily decrease after age 30, a fact implicated in the age-related decline in physical and mental function.⁵ Thus, both groups have been following the developments, or lack thereof, of a class of drugs called GH secretagogues.

Several pharmaceutical companies, large and small, have developed GH secretagogues after it was discovered that small peptide fragments of the larger protein, growth hormone-releasing hormone (GHRH) can stimulate GH release from the pituitary.⁶ GHRH is a hormone produced in the hypothalamus, the gland in the brain that regulates many hormone levels. When the hypothalamus detects conditions that require the release of more GH, it releases GHRH, which travels directly to the pituitary to stimulate GH release. GHRH is too large a protein to be administered orally (meaning it can't be taken as a pill), but smaller fragments of GHRH can be effective orally. Most of the early secretagogue work revolved around fragments of GHRH.

Other stimulators of GH have been discovered, including a hormone produced by the stomach called ghrelin (pronounced gray-lin). Ghrelin interacts with a different class of pituitary receptors than GHRH, promoting GH release through a separate pathway.⁷ Ghrelin's name is a shortened form for GH-releasing protein. Pharmaceutical companies, including Pfizer, hastened to find novel drugs that might take advantage of the ghrelin pathways for stimulating GH release. Among these was a drug called capromorelin.^8,9

An Unsuitable Candidate

Capromorelin is being referred to in the past tense, as Pfizer discontinued developing the drug in 2002 due to limited efficacy and reports of side effects that made it an unsuitable candidate for FDA approval.¹⁰ It's very difficult to obtain FDA approval for drugs designed to treat signs and symptoms of normal aging, as the FDA doesn't consider aging to be a disease and maintains very high standards for safety and efficacy.¹¹ Other pharmaceutical powerhouses have also terminated their GH secretagogue programs, including Merck and Bristol-Myers Squibb.^10,11

However, capromorelin recently made the news as one of the clinical investigators participating in a Pfizer study reported on results at the 2006 International Congress of Neuroendocrinology in Pittsburgh. Dr. George Merriam, professor of medicine at the University of Washington and a physician with the VA Puget Sound Health Care System, presented the findings of a multi-site study, which enrolled nearly 400 elderly adults between the ages of 65-84. Merriam stated that the subjects gained over 3 pounds of lean mass, improved physical function (activities like walking) and had higher GH and IGF-1 levels; side effects were minor and included fatigue, insomnia and hyperglycemia (high blood sugar).^11,12

What wasn't disclosed in the media reports on this presentation was that Dr. Merriam's data was based on a study that terminated prior to 2002. The impression given most readers was that capromorelin was currently being actively developed and possibly moving toward FDA approval. A conversation with Stephen Lederer, senior director of media relations at Pfizer Global Research and Development confirmed that capromorelin was no longer being developed as of 2002, and that Dr. Merriam's data related to earlier clinical trials. Mr. Lederer noted that there was enthusiasm among some of the clinical investigators for further developing capromorelin, but that an exhaustive analysis by Pfizer deemed it an unsuitable candidate after $71 million had been spent on the project.

Needless to say, it was not a decision made lightly. Mr. Lederer provided the following quote: "We greatly respect Dr. Merriam and the other investigators we work with and value their opinions. In this case, we firmly believe the decision to discontinue was appropriate and was in the interests of patients. We saw some increase in body mass, but no significant improvement in physical function. We believed that the lack of functional improvement and the side effects we observed were unacceptable in a chronic-use medicine. Our considerable experience led us to believe that this risk/benefit ratio would not have been acceptable to regulatory agencies for the prevention of age-related declines in physical performance.¹³

A Growing Demographic

On a more positive note, the rights to Bristol-Myers Squibb's secretagogue program have been purchased by Elixir Pharmaceuticals, a smaller company that focuses on age-related diseases, so it's possible that future developments in this area may be announced.¹⁴ The growing demographic of aging baby boomers and the recognition of further benefits associated with preventing age-related GH decline such as improved mental performance, in addition to the physical benefits, ensure continued public interest in the field.¹⁵

Given the lack of an available secretagogue and the efficacy of GH and the natural stimulus to GH provided by exercise, why would any athlete be interested in GH secretagogues?¹⁶ Previous experiences with dietary supplements claiming to promote GH release have been variable, with many providing little apparent benefit. Amino acid-based GH releasers, though capable of inducing a greater GH release at rest, appear to actually inhibit exercise-induced GH release.^17-19

Pharmaceutical GH secretagogues may offer several benefits that aren't currently available with GH. First, a number of orally active formulations have been developed. Though often short-acting, continuous-release capsules have been produced- even in the case of capromorelin. It's unclear whether a sustained, long-acting version of a secretagogue would provide any clinical benefits, as GH is released in several short bursts throughout the day rather than as a long, continuous flow. Nonetheless, injections could be avoided, reducing cost, storage problems, injection site trauma or infection, as well as any related pain or discomfort. Second, the other "regulators" of GH release would still be active in the body, reducing the risk of side effects related to GH excess. It's important to note that some side effects were still noted in Dr. Merriam's study group, but it's possible that a younger population may better tolerate the therapy. The observation of a higher risk of side effects in older subjects has been noted with testosterone therapy in men and estrogen therapy in women.^20,21

The Return of Cadaveric GH

The last notable benefit relates to athletes who might abuse GH in sports doping. At this time, the International Olympic Committee (IOC) doesn't ban GH secretagogues as they're not commercially available, though expect WADA and related groups to respond more pro-actively after the revelations exposed during the BALCO scandals. While it's obvious that GH secretagogues could be used by athletes for the purpose of increasing GH, it's also possible that GH secretagogues could be used, even at this time, to foil the proposed GH-detecting algorithms suggested by WADA, allowing athletes to use the more potent and effective method of recombinant GH injections.

Here's how it might work: Currently, it's impossible to detect exogenous GH doping, as the recombinant product is identical to one form produced in the body.^22,23 WADA has proposed to test athletes' blood (as opposed to urine, which is used in nearly every other test) for two different sets of markers. First, WADA would check to see if the form of GH present in commercially available products is present in greater amounts, compared to the other forms, than is naturally seen.²⁴ This is similar to the 4:1 ratio of testosterone:epitestosterone that's used in some screens and was defeated by use of the "the cream." The cream contained both testosterone and epitestosterone, which lowered the testosterone:epitestosterone ratio back down to accepted levels, preventing a positive drug test.[Author's note- the ratio of testosterone to epitestosterone is the doping detection screen that prompted the allegations of testosterone use by 2006 Tour de France champion Floyd Landis].²⁵

GH secretagogues could stimulate the release of natural GH, including all the isoforms tested for by the proposed WADA plan, restoring isoform ratios back to accepted levels. Of course, this would have to be titrated individually with each athlete, making it expensive, unless they were willing to chance it on a general program. This assumes that illicit manufacturers aren't providing GH products that include a natural combination of the various isoforms. One deadly risk that WADA may actually be propagating is the return of cadaveric GH.

Prior to the discovery of a method of producing GH via recombinant methods (meaning in a laboratory), GH was obtained by extracting it from the pituitary of dead people. This now-banned source, while once valuable to children being treated with the extract, exposed them and doping athletes to the risk of contracting a deadly disease called Creutzfeldt-Jakob disease, similar to mad cow disease.^26,27 There's been at least one case of a French bodybuilder contracting Creutzfeldt-Jakob, possibly from cow-derived, cadaveric GH extract or tainted meat imported from Great Britain (England had an epidemic of mad cow disease at the time) or sporadically- as others of that era caught the disease.^28,29 The French bodybuilder died at the age of 26.

The second leg of the GH-detection algorithm wouldn't be circumvented, as it looks for markers of GH action to determine if supraphysiologic GH levels existed in an individual athlete, such as insulin-like growth factor-1 (IGF-1) and type III procollagen (P-III-P).³⁰ Considering that most athletes are healthy, active and young, it's likely that the threshold will have to be set fairly high. This would limit the total benefit that could be attained through GH and GH secretagogue use, though the window of opportunity would be greater for older athletes. Many athletes are extending their careers into their late 30s and early 40s, making this more relevant with each passing year.

Offering Great Promise to the Aging & Athletic

This article doesn't advocate the use of GH or GH secretagogues for doping purposes. Instead, it's a response to reports of archived data that has raised the hopes of those facing declining function due to aging, or those hoping for a safer and more convenient means of promoting optimal GH to improve appearance and performance. It also raises a prospective inquiry regarding attempts by doping athletes to violate the ethics and rules of organized sports.

GH therapy offers great promise to the aging and athletic. Secretagogues, such as capromorelin, may provide a bridging therapy to those who either choose to avoid GH injections, or seek less expensive alternatives. At this time, there's no pharmaceutical secretagogue commercially available, and it remains to be seen if any of these oral drugs will provide similar effects to GH over the long-term. Further, it will be interesting to see if protocols will be developed allowing those first experiencing signs and symptoms of GH decline in their 30s and 40s to access either GH or GH secretagogues. As has been suggested with research involving the hormones testosterone and estrogen, introducing the therapy early, rather than waiting until frailties manifest, may reduce risks. As the first of the baby boomers enter their 60s, perhaps this politically affluent generation will prompt changes in legal and professional restrictions.

References:

1. Morley JE, Unterman TG. Hormonal fountains of youth. J Lab Clin Med, 2000;135:364-6.
2. Llewellyn W. Human Growth Hormone (somatotropin). Anabolics 2005. Body of Science Press, Jupiter, FL;2005:288-90.
3. Brundett R. Shortt gets jail; players not off hook. The State [South Carolina], 2006 July 18.
4. Surya S, Symons K, et al. Complex rhymicity of growth hormone secretion in humans. Pituitary, 2006 Jul 15;[Epub ahead of print].
5. Mooradian AD, Morley JE, et al. Endocrinology in aging. Dis Mon, 1988;34:393-461.
6. No Author Listed. Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN, KP-102D, KP-102LN. Drugs, R D 2004;5:236-9.
7. Kojima M, Hosoda H, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature,1999;402:656-60.
8. Carpino PA, Lefker BA, et al. Pyrazolinone-piperidine dipeptide growth hormone secretagogues (GHSs). Discovery of capromorelin. Bioorg Med Chem, 2003;11:581-90.
9. Carpino PA, Lefker BA, et al. Discovery and biological characterization of capromorelin analogues with extended half-lives. Bioorg Med Chem Lett, 2002;12:3279-82.
10. Cohen F. Quest for youth: How research on anti-aging pill lost momentum. Available at http://blog.crownstoneinsights.com/notes/archive/2006_07_01_archive.html, accessed July 28, 2006.
11. Fox M. Drug, blood provide clues to healthy aging-meeting. Reuters News Service, 2006 Jun 21.
12. Reedy J. Growth hormone stimulators improve physical function in older adults. Public Release - University of Washington, via EurekAlert! news service.
13. Lederer S. Personal communication via phone and email, July 25, 2006.
14. Elixir Pharmaceuticals. Elixir Pharmaceuticals licenses novel growth hormone secretagogue compound from Bristol-Myers Squibb for treatment of metabolic disorders. 2005 Apr 28. Press Release available at http://www.elixirpharm.com/company/pr/squibb_050205.pdf, accessed July 28, 2006.
15. Arwert LI, Veltman DJ, et al. Memory performance and the growth hormone/insulin-like growth factor axis in the elderly: a positron emission tomography study. Neuroendocrinology, 2005;81:31-40.
16. Weltman A, Weltman JY, et al. Growth hormone response to graded exercise intensities is attenuated and the gender difference abolished in older adults. J Appl Physiol, 2006;100:1623-9.
17. Marcell TJ, Taaffe DR, et al. Oral arginine does not stimulate basal or augment exercise-induced GH secretion in either young or old adults. J Gerontology, 1999;54A:M395-399.
18. Surninski RR, Robertson RJ, et al. Acute effect of amino acid ingestion and resistance exercise on plasma growth hormone concentration in young men. Int J Sport Nutr, 1997;7:48-60.
19. Besset A, Bonardet A, et al. Increase in sleep related GH and Prl secretion after chronic arginine aspartate administration in man. Acta Endocrinol (Copenh), 1982;99:18-23.
20. Bhasin S, Woodhouse L, et al. Older men are as responsive as young men to the anabolic effects of graded doses of testosterone on the skeletal muscle. J Clin Endocrinol Metab, 2005;90:678-88.
21. Naftolin F. Prevention during menopause is critical for good health: skin studies support protracted hormone therapy. Fertil Steril, 2005;84:293-4.
22. McHugh CM, Park RT, et al. Challenges in detecting the abuse of growth hormone in sport. Clin Chem,2005;51:1587-93.
23. Rigamonti AE, Cella SG, et al. Growth hormone abuse: methods of detection. Trends Endocrinol Metab,2005;16:160-6.
24. Project Review. Transition from research lab to ISO-certified optimization and production of differential immunoassays for the detection of GH-doping in sports based on the isoform approach. World Anti-Doping Agency. Available at http://www.wada-ama.org/rtecontent/document/DrSoehnge.pdf, accessed July 28, 2006.
25. Mann D. Innocent reasons for Landis dope test? WebMD Medical News 2006 July 27. Available at http://www.webmd.com/content/article/125/116062, accessed July 28, 2006.
26. Brown P, Gajdusek DC, et al. Potential epidemic of Creutzfeldt-Jakob disease from human growth hormone therapy. N Engl J Med, 1985;313:728-731.
27. Deyssig R, Frisch H. Self-administration of cadaveric growth hormone to power athletes. Lancet, 1993;341:768-769.
28. Chazot G, Broussole E, et al. New variant of Creutzfeldt-Jakob in a 26-year-old French Man. Lancet, 1996;347:1181.
29. Verdrager J. New variant Creutzfeldt-Jakob disease and bovine pituitary growth hormone. Lancet, 1998;351:112-3.
30. Sonksen & Holt. The development of methodology for detecting growth hormone in sport:GH2004. World Anti-Doping Agency. Available at http://www.wada-ama.org/rtecontent/document/A1_2002_results.pdf, accessed July 28, 2006.

FAT ATTACK: EAT FAT, BURN FAT

Posted by: Unknown توقيت نشر: 18:05 / comment : 0 BURN FAT, fat, FAT ATTACK: EAT FAT, Fat Loss, life, loss, man

Pull Quote: While some fats are more prone to be taken up by fat (adipose) cells and stored as body fat, others are more likely to alter metabolism to favor fat-burning.

For many years doctors and nutritionists were steering people away from “dreaded” fat assuming that fat in the diet was directly converted into body flab. Because of this, there was a proliferation of low- or fat-free products taking over the supermarket aisles in the 80s and 90s. Fat-free salad dressing, light peanut butter and low-fat yogurt were among the many items that were supposed to be better for us because they got rid of the fat. And what happened with the mass consumption of these products? Obesity rates skyrocketed and reached epidemic proportions. Other than the fact that many reduced-fat items replaced the fat with sugar, one reason for this trend toward expanding midsections was the false assumption that all dietary fats were alike.
It now seems apparent that the body handles various fats differently. While some fats are more prone to be taken up by fat (adipose) cells and stored as body fat, others are more likely to alter metabolism to favor fat-burning.

Fish Oil
Any devoted reader of this publication will, by now, know that the fats in fish have a wide range of health benefits. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are found in high amounts in fatty, cold-water fish such as salmon, sardines and mackerel, have been shown to protect the heart from disease by reducing inflammation, blood triglycerides and arterial plaque instability. Cancer, eye disease, Alzheimer’s and depression7,8 also appear to be on fish oil’s hit list. However, little fanfare has been paid to fish oil’s ability to alter metabolism and increase fat burning.
Many of the health benefits attributed to long-chain polyunsaturated fats such as DHA and EPA are a result of their ability to alter our gene functioning using various mechanisms. These include changing the makeup of cell membranes, changing the transcription of genes and impacting the levels of calcium found within our cells.9,10,11,1213,14,15 By altering our genes in a positive way, DHA and EPA are very effective at combating a vast array of serious conditions, one being that of excess body fat.16
One outcome of this regulation of gene expression is that DHA and EPA increase the rate of fatty acid oxidation (fat-burning) by increasing the activity of enzymes and receptors in the liver involved in fat breakdown and oxidation, while decreasing the activity of those associated with fat storage.17,18,1920,21 All of this improves both fatty acid and glucose metabolism.10,15,1820,23 In other words, they can reduce fat cell proliferation by limiting both the expansion (hypertrophy) and division (hyperplasia) of fat cells.24,25
Fish oil can also indirectly affect our fat stores by improving skeletal muscle sensitivity to insulin.10,22,23 Insulin resistance is a serious contributor to fat storage by causing an unusual increase in blood glucose levels. Eventually this glucose can be stored as fat in the fat cells.
Consuming three to four servings of fatty fish per week is what many health experts recommend in order to obtain enough DHA and EPA. However, taking a daily fish oil supplement may be the best way to reap all the rewards of this amazing fat source. Concerns over contaminants present in fish such as farmed salmon and the reality that the majority of us simply don’t eat enough fish in any given week, makes supplementation a viable option. ConsumerLab.com, which is an independent supplement testing organization, found that all the fish oil supplements they tested were free of contaminants, such as mercury and PCBs.

Oleic Acid
Oleic acid is a monounsaturated fat (mono meaning it contains one double bond) found in various vegetable oils that’s alternatively known as an omega-9 fatty acid. Like DHA and EPA found in fish, oleic acid appears to alter metabolism in favor of fat oxidation and away from fat storage.26,27,28 The opposite can be said for palmitic acid— a fully saturated fat present in fatty meat, butter, cream, full-fat dairy and baked goods— that it is more prone to being stored compared to unsaturated fatty acids.29,30
These characteristics were highlighted in a recent study published in the American Journal of Clinical Nutrition, which found that after 28 days, an increase in the intake of saturated palmitic acid decreased fat burning and daily energy expenditure in healthy subjects, whereas a decrease in the consumption of palmitic acid intake and a increase in oleic acid intake had the opposite effect, resulting in an improved body composition. The researchers concluded that increases in dietary palmitic acid may alter our gene expression in such a way that increases the risk of obesity along with insulin resistance, whereas oleic acid may do the reverse when consumed in reasonable amounts.26
Oleic acid’s ability to turn up the heat is particularly apparent following a bout of exercise.31,32,33 Exercise, especially high-intensity exercise, can change your metabolism from favoring fat storage to favoring fat burning for several hours afterward while the body takes part in recovery processes such as lowering heart rate and replacing used up energy stores.34 However, it appears that this outcome is much more likely to occur if, following exercise, you consume monounsaturated fat in the form of oleic acid as opposed to saturated fat in the form of palmitic acid. Therefore, when you are finished hitting the weights, give those French fries a break and instead opt for the baked potato drizzled with olive oil.
Oleic acid has also been found to have a faster oxidation rate than the other unsaturated fatty acid known as linoleic acid, which is an omega-6 fat is found in high amounts in soybean and corn oil.35 It should be noted that these oils are commonly used in restaurants, fast-food joints and many processed foods. Because of this, most Americans consume much more linoleic acid than oleic acid and omega-3 fatty acids. This isn’t ideal, as linoleic acid appears to be more likely to be retained in the body following a meal, due to its lower propensity for being used to generate energy.
Keep the important advantages of oleic acid in mind when you’re reading about the Mediterranean diet since this relatively high-fat diet is very high in oleic acid. This is because of the generous use of olive oil in populations who practice this way of eating. The fat-burning characteristics of oleic acid may shed more light on why the traditional Mediterranean diet is so healthy and why individuals from countries such as Greece and Italy who follow it tend to be slimmer than Americans.
What all this means is that you should consume a good chunk of your daily fat as monounsaturated fat (oleic acid) to help better manage your metabolism. Major dietary sources include olive oil, canola oil, peanut oil and the "high-oleic" safflower and sunflower oils. Oleic acid is also found in various amounts in avocados, nuts, cocoa butter and nut butters.

Coconut Oil
Lately, coconut oil has been flying off the shelves of health food stores. Once branded Public Enemy Number One by health practitioners, it appears that this oil is making a healthy comeback. One reason is the belief that it helps shed body fat.
Medium-chain triglycerides (MCTs), which make up over 50 percent of the fat in coconut oil in the form of lauric acid, are thought to be one tool in the battle of the bulge. MCTs, in contrast to long-chain triglycerides like palmitic acid, increase energy expenditure by being digested and absorbed much more quickly as a result of their unique six- to12-carbon length (long chain fats contain over 12 carbons). Their unique structure also alters the expression of genes involved in the uptake of fat into fat stores. As a result, MCTs are largely converted (oxidized) to energy in the liver and muscle instead of entering fat (adipose) tissue resulting in a negative energy balance.36,37,38,39,40 In addition, MCTs may bring about a greater feeling of satiety, leading to a reduction in calorie intake.39 Whether all this translates into fat loss and the prevention of weight gain as a result of coconut oil consumption and just how much oil would need to be part of the diet for this to occur, is yet to be determined as there’s no solid data studying coconut oil’s effect on fat metabolism.

Enova Oil
Enova (www.enovaoil.com) is a new cooking oil made from a mixture of soybean and canola oil. According to the makers of EnovaÔ, the difference between this cooking oil and others is that most oils used for cooking contain fat molecules, which are primarily triglycerides, while Enova has a higher concentration of diglycerides. The differences in chemical structure and shape may mean that the fat in this new oil is more likely to be oxidized instead of being stored.41 While it remains to be determined what real impact this oil may have on body fat regulation, one concern is that this oil is higher in polyunsaturated fat than other common cooking oils such as pure canola or olive oil. Polyunsaturated fats are less stable when exposed to heat than monounsaturated fats and can produce damaging free radicals when heated to a high temperature. Cell damage from free radicals can lead to cancer, age-related vision loss and other health problems. Olive and canola oils higher in monounsaturated fat are likely more heat stable and, therefore, might be a better option for cooking up that stir-fry.

Fat Recommendations
? Obtain between 25 and 30 percent of total calories from fat.
? Use extra-virgin olive oil (high in oleic acid) for salad dressings. Olive oil is also good fat choice after a workout.
? Avoid fatty processed foods high in saturated and trans-fat.
? Use heat-stable virgin coconut oil for high-heat cooking.
? Consume fatty fish at least three times per week and/or use a daily fish oil supplement.

References

Slim for Life: 10 Strategies to Lose Fat and Keep It Off

Posted by: Unknown توقيت نشر: 01:13 / comment : 0 fat, life, loss, slim, Slim for Life: 10 Strategies to Lose Fat and Keep It Off

Use fat to burn fat.

Trying yet again to lose those last 10 pounds? We hear you. In fact, 50 percent of women say that within six months they gain back any weight they've managed to ditch. And more than a quarter have dieted so many times they've lost track of the number. Well, get ready to stop the endless yo-yoing: Science has finally come up with simple, groundbreaking solutions for lasting weight loss. We checked in with the top experts in the field and scoured the latest research to bring you the skinny on everything you need to reach your slim-down goals and stay there.

Make your fat burn fat.

Seriously: Your flab can help you shed pounds. How? Just as there's more than one kind of fat in food, there's more than one type in your body. White fat is the bad stuff you want to zap. But a second kind, brown fat, actually torches calories. "Up to 80 percent of adults have brown fat deposits in their bodies," says Aaron M. Cypess, MD, PhD, an assistant professor of medicine at the Joslin Diabetes Center and Harvard Medical School. This good fat is powerful because it's packed with mitochondria, the parts of cells that generate heat. When activated, as little as two ounces of brown fat can gobble up as much as 20 percent of your body's calories.

Exercise is one of the best ways to get your brown fat in gear. In a study, scientists at Harvard's Dana-Farber Cancer Institute discovered that working out releases a hormone called irisin, which converts white fat to brown. Exercise for a half hour at least five days a week to turn up the burn.

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