Hormones and Weight Gain
Menopause weight gain also called hormonal weight gain, is a true struggle that very few talk about. Rarely do medical professionals emphasize the health risks associated with it. More likely than not, a healthcare provider will suggest that too many sweets or a decrease in exercise are the culprits. Sure, that’s maybe part of it, but during menopause, the drop in hormones plays a bigger role in women’s transition from an hourglass body to an apple-shaped body.
At age 40, most women don’t want to think about menopause. But hormones will continue to reduce their levels whether that reduction is recognized or not. Ignoring what is happening to your body is not a method to prevent weight gain. Weight loss after 40 is possible. Working with, not against, the hormonal changes can make active weight loss possible. By understanding the true source of weight gain, you can shed excess weight and prevent further weight gain; ultimately helping you to feel happier and healthier.
People often assume that menopausal weight gain is ‘natural,’ and in some ways it is. But ‘natural’ does not necessarily mean healthy or desirable. As women age, maintaining their usual body weight becomes more difficult. Many women gain weight during and after their menopause transition, especially around their abdomens. But it’s not healthy, and it does NOT have to be inevitable.
Menopausal weight gain can be prevented, and reversed, with a proactive approach that deals with the natural decreases in the hormones estrogen, progesterone, and testosterone. Of course, paying attention to healthy eating habits, and leading an active lifestyle is also important.
During perimenopause and menopause, it can feel like the cards are stacked against maintaining a trim physique. But for long term health, it is important to keep the body and waistline trim. Hormonal replacement therapy (HRT) can do just that. Hormones work together to increase, or decrease, appetite and fat storage. If the hormone system doesn’t work properly, women can struggle with weight issues on an ongoing basis. Fortunately, taking HRT, improving diet, and adding a few lifestyle changes can have powerful effects on weight loss.
Menopausal weight gain is directly related to the decrease in the production of hormones. But to maintain a healthy weight, a delicate balance of all hormones is required. If certain hormones are off-kilter or reduced, weight gain often results.1,2 Hormones are simply a communication method that the body uses to tell itself what to do. It’s like that old telegraph game…if one hormone is off and can’t communicate properly, it alters other communication down the line. Even small shifts in hormone levels can have significant effects.
Why is it so Critical to Prevent Weight Gain at Menopause?
Throughout the reproductive years, women may notice weight gain around their hips and thighs. However, at menopause, women tend to gain weight around their abdomen and upper back. This shift in where fat is deposited is due to hormonal changes brought about by menopause. While the genetic factors related to weight and fat distribution can’t be changed, women can control menopausal weight gain by reversing the decrease in hormones.10
Menopausal women taking HRT tend to have less body fat, especially abdominal fat.3 Simply put, most women are overweight at midlife because their hormones are out of whack, and that type of weight gain is dangerous. The health implications of weight gain at menopause cannot be overstated. Excess weight, especially around the midsection, is called ‘visceral fat’.
Visceral fat cells can set off inflammation, and increase insulin resistance. Visceral fat gets worse with depression, stress, poor sleep, smoking, and drinking fructose-sweetened beverages. If that’s not enough, menopausal weight gain increases the risk of:
High blood pressure
Cancer – specifically colon, breast, uterine, esophageal, kidney, and pancreatic.
Type 2 diabetes
Beyond these effects, decreased hormones and excess weight tend to lead to lower libido through vaginal changes, reduced energy, reduced mobility, poor self-image, and so much more.
Say goodbye to hormonal weight gain.
Top 10 Way to Prevent & Reverse Menopause Weight Gain
Try Hormone Replacement Therapy (HRT)
Menopausal weight gain and the inability to lose weight are based on a litany of factors. The decrease in estrogen and progesterone during menopause are the primary factors. The calories in vs. the calories out aren’t just the whole story for menopausal women. Yes, calories matter, but in menopause and perimenopause, hormones matter more. Taking HRT can have powerful effects on preventing weight gain. A thorough review of the hormones and how HRT can help normalize the levels are presented in the next section.
Stop the Fatigue Due to Night Sweats
Night sweats associated with perimenopause and menopause can create an endless cycle of fatigue. People eat more when they are tired.3 Without enough sleep, people snack more and consume more calories. When they are sleep deprived, women’s levels of appetite hormones increase (ghrelin and cortisol).7
Very few people function well on less than 7 hours of sleep. Sleeping 7 to 8.5 hours every night is critical to reducing stress. If sleep is regularly disrupted, the stress hormone ‘cortisol’ increases, and weight gain ensues. HRT has been shown to reduce night sweats more effectively than any other treatment, allowing for restful sleep, decreased anxiety, and weight loss.3 A fan, cooling pillow, or white noise machine are all great options to improve sleep.
Regain Lean Muscle Mass
As people age, their muscle mass typically decreases while fat levels increase.2 When muscle mass decreases, so does the metabolism. When metabolism drops, so does the number of calories needed per day. If a woman continues to eat as she always has, and doesn’t increase physical activity, weight gain is inevitable.
When muscle mass decreases, a woman can burn 500 fewer calories per day. At that rate, she would gain 1 lb per week or 52 pounds in just one year!
Starting at age 30, women will naturally lose about 1/2 pound of muscle mass per year. By age 50, that can be 10 lbs of lost muscle, and likely, fat has replaced the muscle.
We know that muscle burns about 3x more calories than fat. If a muscle mass is increased (or returned to pre-menopausal levels), losing weight can be much more realistic. Working out to gain muscle can help decrease the severity of weight gain and can assist with weight loss. Try strength training exercises at least twice a week. To slow down aging, it’s important to maintain or improve lean body mass since aging begins in the muscles.17
Switch the Workouts
Unfortunately, the body doesn’t burn as many calories while walking on the treadmill for 30 minutes at age 55 as it did when aged 35. The same work just doesn’t give the same benefit. So, it may be time to change it up. Like a lifelong swimmer who barely breathes hard after a mile-long swim, the efficiency of being good at something is great, but it burns fewer calories. Changing it up – trying new classes or new challenges – may help to overcome a workout lull.
Permit Mood & Anxiety Changes
Women in menopause have an increased rate of anxiety and depression. Societal norms still adversely impact the willingness of women to seek treatment for mood and anxiety changes. Suicide rates are at their highest for women in their menopause years.
Research shows that those who suffer from depression and anxiety are more likely to gain weight over time and become obese than those who don’t. At appropriate levels, progesterone acts as a natural antidepressant and can enhance mood and relieve anxiety. It stimulates the ‘feel-good’ center of the brain. So, if progesterone levels drop, it is easy to understand why anxiety and depression can follow.17
Progesterone starts to drop in a woman’s 30s, and during perimenopause, the levels drop more quickly. Research has shown that by supplementing progesterone, women can improve anxiety, irritability, and nervous tension.17,18,19 Progesterone appears to be the most potent anti-anxiety hormone for menopausal women; these positive vibes can only help with weight loss.
Tune In to Taste Expectations
There are four basic tastes on the human palate: sweet, sour, bitter, and salty. The ability to sense these tastes is influenced by blood hormone levels. Sensitivity to various tastes changes with menopause. The ability to taste sweet decreases when estrogen levels drop and the sensitivity to bitter tastes decreases with lowering progesterone.3 Both of these hormones drop precipitously with menopause.
Each human is born with nearly 10,000 taste buds, but as women age, the number of taste buds decreases and the remaining taste buds shrink in size. Women even produce less saliva as they age. Since saliva is needed to emulsify food, and help the taste buds to sense the incoming taste, with reduced saliva there is reduced taste as compared to younger days.
Less taste often leads to eating more in an effort to be satisfied. Choosing foods high in butter, salt, and even fine wines, and expensive cuts of meat will yield more flavor, but they also are filled with more calories
Drinking sugar-sweetened beverages, including juices, energy drinks, flavored waters, sweetened coffee, and tea is a natural remedy for a decreased sense of taste. But those calories can account for nearly 300 calories a day in the average American diet or 31 lbs in a year.
Lack of exercise can certainly contribute to menopausal weight gain. Physical activity, which should include vigorous, aerobic exercise as well as strength training, will help shed weight and prevent weight gain.
Whether menopausal women are moving less due to lack of energy, embracing a slower pace of life, or not having kids to chase after, many are sitting for the majority of the day. This sedentary lifestyle makes losing weight quite difficult. Sitting too much has been called the new ‘smoking’ with regards to its adverse effect on overall health.
Exercising vigorously for 4 hours a week can negate a sedentary lifestyle’s health risks. Additionally, walking for a few minutes, like getting up from the desk, can make all the difference. Smartwatches can be programmed to remind women that it is time to stand up. Short bursts of energy throughout the day are considered effective ways to prevent weight gain.
It can last for mere seconds or for several minutes. Moving while talking on the phone or just taking a break every hour from sitting, some people call this ‘exercise snacking’.25 Exercise snacking several times a day can lead to meaningful gains in fitness and overall health. That includes even just 4-second bursts of exercise to improve fitness. Exercise does not have to be considered a special thing set aside at a certain time of day.
Regulate Metabolic Changes
Women lose tissue (bone, muscle, etc.) as they age. It is natural, but there is much that can be done to counteract the loss. With a steady loss of bone and muscle, the body significantly reduces resting metabolic rate (RMR). RMR is the number of calories the body needs to complete daily activities. Too many calories, fat gets stored. Too few calories and stored fat gets used, and energy lags. If all of the stored fat is used up, the body will start to burn protein in the form of muscle.
Menopausal women will experience a reduction in RMR, which can trigger weight gain and changes in the body’s makeup. The result is more fat around the midsection and less muscle.
Accept that the Glory Days are Days Past
With age, the things that women used to do to effectively burn calories and stay fit are not always available. Because of overuse or injury, bones and joints often don’t allow for a quick run at the park. There are many sports and activities that can’t happen anymore in middle age.
With a mental shift, the things that once were a person’s ‘identity’, “I was an X player,” can be replaced with a new activity. It takes energy, bravery, and compunction to get there, but it can make all the difference in weight loss or maintenance and overall wellness.
Eat and drink less
A woman in her 50’s can expect to burn about 200 fewer calories per day than she did in her 30’s and 40s. This adds up to an easy 20 lb. weight gain per year. To reduce calories without skimping on nutrition, choose more fruits, vegetables, and whole grains, particularly those that contain more fiber.
Alcoholic beverages add excess calories and increase the risk of gaining weight. With menopause, it is harder to metabolize alcohol. Many women say that drinking makes mood swings, hot flashes, and insomnia worse. Doctors also warn that alcohol can be more dangerous as women age.24
Personalized hormone treatments. For you.
Why Take Hormone Replacement Therapy?
Most women in perimenopause and menopause are struggling with their weight on some level. Too much weight, weight in the wrong places, and can’t seem to exercise enough to keep it off. Even worse, the diets and exercises that once worked so well, or the new ones that claim to be the panacea, are often harsh and can escalate hormonal imbalances.14
As we discussed, hormones control metabolism and weight balance. The most effective way to get hormones back on track, halt the ever-present scale creep, and return to a healthy weight is to correct hormonal imbalances with HRT. Once hormones are back in balance, weight loss can begin.
Hormone regulation is complicated. The body’s hormones are all interconnected. The hormone systems must work in harmony and continually rebalance in response to physical and emotional events in a woman’s life. Perimenopause and menopause are the phases of a woman’s life when she will experience huge swings in hormone levels. Specifically, hormones related to:
Reproduction, and the monthly menstrual cycle (estrogen, progesterone, testosterone),
Adrenal gland functioning (cortisol, adrenaline),
Thyroid gland activity (TSH, T3, T4).
If perimenopausal and menopausal women fail to address the hormonal root causes of weight gain and weight loss resistance, their goals will not be achieved. At perimenopause, women will experience a cascade of hormone imbalances. Since these three hormonal networks impact one another, the results can sometimes be extreme.
This cascade of hormonal imbalance is due to the interplay of all of these hormones. When one goes up, another one goes down. What was once a symphony of hormones playing a pretty good tune, suddenly becomes a screeching cacophony that can crescendo into a world of problems, including weight gain.
Excess, low, or blocked levels of the hormones cortisol, insulin, leptin, ghrelin, progesterone, estrogen, thyroid, and testosterone throw that symphony into hormonal dissonance. By starting HRT, a woman can begin the process of repairing the imbalances of the hormones and can once again play in harmony.
Details About the Hormones of Weight Gain
Estrogen: Estrogen is one of the two (mostly) female sex hormones, and is responsible for the beginning of puberty, the menstrual cycle, and when it drops perimenopause begins. Beyond that, estrogen has many other functions, including:
Helping to control blood cholesterol levels,
Promoting bone health,
Protecting the brain, and regulating mood,
There are three main types of estrogen:
Estrone, or E1, is produced after menopause.
Estradiol or E2, produced in the childbearing years.
Estriol, or E3, which the body produces during pregnancy.
Symptoms of low estrogen
Insomnia and night sweats,
Vaginal dryness and thinning
Moodiness or irritability
Dry and sagging skin
At appropriate levels, estrogen can strongly regulate and reduce food intake, which translates to weight. Too little or too much estrogen and weight gain often result. Studies have regularly shown that following estrogen replacement, like with HRT, food intake decreases significantly. Replacing the decreased estrogen in a menopausal woman can likely reverse excess food intake.1
Estrogen and progesterone are called “sex steroid hormones.” Both are involved in the metabolism, accumulation, and distribution of fat.1 Produced mostly in the ovaries, estrogen’s primary role is to maintain the female reproductive organs. But estrogen has lots of other responsibilities, like regulating feelings of hunger, keeping the pace of the metabolic rate, and the accumulation and distribution of fat.1
Past the age of 35, women enter perimenopause and estrogen drops, which can cause depression and low libido.
Progesterone: Progesterone acts as a natural antidepressant and can enhance mood and relieve anxiety. It stimulates the brain’s feel-good’ center. So, when progesterone levels drop with menopause, it is easy to understand why anxiety can become a major menopause symptom.17 Progesterone appears to be the most potent anti-anxiety hormone for menopausal women.18,19
While there are many causes of anxiety, progesterone deficiency is the main factor during menopause. Anxiety is defined as a state of uneasiness, and symptoms include terms like: nervous, irritable, scared, fearful, worrisome, panicky, ill at ease, or worry. Often, the anxiety can lead to a panic attack accompanied by physical symptoms like a pounding heart, sweating, and rapid breathing. When excessive anxiety occurs daily, it becomes disabling.
Sometimes healthcare providers don’t correlate anxiety with menopause and the drop of progesterone. But they should. Instead, they will likely prescribe anti-anxiety drugs without correcting for the lowered progesterone. The side effects of these anti-anxiety drugs can include fatigue, memory impairment, insomnia, decreased libido, changes in appetite, dizziness, and yes, anxiety. All of which menopausal women are already battling.
When progesterone levels are restored to normal with bioidentical progesterone, women have noticed anxiety relief, decreased irritability, and less nervous tension.17,18,19
Insulins Impacts on Weight: Insulin is a critical hormone when it comes to weight loss, weight gain, and fat storage. Insulin imbalances can lead to weight gain, obesity, and eventually, type 2 diabetes. Insulin resistance leads to high blood sugar. This is age-related, at least in part due to lower circulating hormone levels. When the body does not understand that the sugar (glucose) should go into the cells, the liver will grab the sugar and convert it into fat. Insulin resistance usually causes weight gain and what some people call a ‘sugar addiction.’
Insulin is secreted in small amounts throughout the day and in larger amounts after meals. Made by the pancreas, insulin is responsible for storing blood sugar (glucose), and regulating how your body uses the sugar. For example, after a large meal, a dose of insulin is released into the bloodstream. This helps the sugar from your meal get taken up by the needy cells. Then, blood sugar levels will return to normal. Insulin also regulates fat storage, specifically how much fat to store, where to store it, and how much to use as energy.
When there isn’t enough estrogen, like what women experience in menopause and perimenopause, the result can be complex metabolic disorders. These imbalances can put a menopausal woman at high risks for life-threatening human diseases, such as type-2 diabetes, cardiovascular disease, and certain cancers.5
Insulin resistance and estrogen deficiency are disorders that are commonly seen together.5 With decreased estrogen production, insulin resistance can occur. Even a slight decrease in circulatory estrogen levels is associated with insulin resistance. It can also increase the risk for cancers, particularly in the organs having high estrogen demand (breast, endometrium, and ovary).5
When a woman reaches post-menopause and has not taken HRT, she will have been estrogen deficient for decades. She will also be at high risk for cancers in other organs.5 HRT improves insulin sensitivity and decreases the incidence of cancer in postmenopausal women. The most recent research reveals the interplay between insulin resistance with prolonged estrogen deficiency and the importance of providing HRT in order to prevent cancers.5
Leptin and Appetite: Leptin is a hormone made by fat cells that can decrease appetite. Leptin signals the brain that a person is full. When working correctly, leptin will send signals to the brain that the body has enough energy stores (body fat), and doesn’t need to eat again. Some call it the ‘satiety’ hormone. If leptin fails to send the right signals, or if the amount of leptin release isn’t accurate, a healthy weight is hard to achieve.6 When ‘leptin resistance’ occurs, the brain doesn’t understand that it doesn’t need to eat anymore, even though leptin is trying to tell it to stop. The result is that the person keeps eating and doesn’t feel full. This kind of misunderstanding can lead to women feeling ravenous even after a full meal.
When leptin levels are balanced, there is good communication between leptin and the brain, and people don’t overeat because they feel appropriately full after a meal. That fullness should last for hours.
Estrogen has long been considered important in eating behavior – the feeling of full or hungry. Part of estrogen’s role in metabolism is to regulate leptin. Too little estrogen, then too little leptin, and everything is thrown off, leading to leptin ‘resistance’ and potentially obesity.1
The Little Known Ghrelin Hormone: Ghrelin is a hormone that increases appetite and plays a role in body weight. Ghrelin is sometimes called the “hunger hormone.” It is released from the stomach, communicates with the brain, and signals hunger. Ghrelin is what helps the body identify that the stomach is empty. It also helps to determine how quickly hunger comes back after eating (generally about three hours). After a meal, ghrelin levels are low and increase as the stomach empties.6 At least, that’s the way it is supposed to work.
HRT has been shown to decrease blood levels of ghrelin, particularly when HRT is taken orally.7 Ghrelin works well in most people who are healthy, and at an optimal weight. In overweight people, ghrelin levels don’t decrease enough after eating to suppress the appetite, and the person will not feel full. There are a couple of ways to balance ghrelin levels including:
Eat protein at most meals,
Avoid sugar, and
Thyroid Gland Has a Critical Job: The thyroid plays a major role in mood and regulating how many calories a person burns – better known as the metabolism.17 If thyroid hormones are low, or not working properly, weight gain, fluid retention, hair loss/thinning, and depression can occur.
Estrogen helps regulate thyroid cells.15 It stimulates thyroid growth, and with too little estrogen, not enough thyroid tissue will be made, leading to irregularities in metabolism.16 Progesterone and thyroid hormones have a mutually dependent relationship. Progesterone can help regulate the amounts of thyroid hormone levels in the blood, and thyroid hormones stimulate the ovaries to make progesterone.16
In many perimenopausal and menopausal women, thyroid levels may be low likely due to decreased estrogen. Adding estrogen back via HRT can help with these imbalances.
Testosterone: While we know a lot about estrogen and progesterone’s role in menopause symptoms, most people don’t think of testosterone. Typically, testosterone is identified as the man’s hormone, but women make and need testosterone. When testosterone levels drop due to menopause, there are significant symptoms for women. To effectively reduce symptoms of menopause, women need to consider testosterone levels.
Testosterone is important for sexual desire and mental reasoning, helps maintain a woman’s muscle mass, and partners with other hormones to regulate the fat distribution and base metabolic rate.22,23 Like estrogen and progesterone, testosterone peaks when women are in their early 20’s. It starts to decline in their 30’s and sharply drops during the menopausal years. The average testosterone levels fall by about 50% by the mid-’50s.22
Low testosterone levels in women create symptoms that are often not properly attributed to decreased testosterone and are often subtle. Decreased libido and a decline in sexual satisfaction are the most commonly recognized symptoms. But low testosterone can also result in fatigue, weight gain, muscle weakness, and mood changes. Because testosterone levels often decrease gradually over time, the symptoms can sneak up on women making it harder to recognize. Although these symptoms can occur throughout a woman’s life, low testosterone during menopause tends to be more problematic as estrogen and progesterone levels also decrease.
Testosterone plays an important role in the development of lean muscle mass. When testosterone declines, muscle mass can decrease, fat can increase, and the metabolic rate drops leading to weight gain. Women with more lean muscle mass burn more calories at rest than women with lower muscle mass – even at the same body weight. Women with lower testosterone tend to gain weight more quickly because they have a lower metabolic rate.
When testosterone replacement is given at normal levels, it is very safe with mild or no side effects. Replacing testosterone during menopause is an important part of hormone replacement therapy. Testosterone replacement can improve mood and wellbeing, help with weight loss, improve cognition, and restore sexual health.
The Stress Hormone Cortisol & Weight Loss: Created in the adrenal glands, cortisol is known as the “stress hormone.” At too high of levels, it also causes belly fat deposits.10 Some people call it the ‘fight or flight’ hormone. It is a protection mechanism that keeps humans out of dangerous situations and safeguards them from threats. If a person is about to get chased by a lion, cortisol skyrockets and that is an appropriate response.
If a person is late for a deadline at work, cortisol levels can jump up, maybe too high for the actual ‘threat’. Cortisol can often be three times too high, leading people’s behavior to be out of balance with the real threat – like constantly racing from task to task, feeling anxious but tired, moody and quick to anger, maybe irritable, and rapidly gaining weight.
While most people don’t have to worry about lions, many people are producing cortisol at levels that are inconsistent with their true life situation because of increased levels of stress. Regardless of whether or not the stress is a lion or a deadline at work, the body releases an abundance of cortisol for both.
When the mind perceives stress cortisol is released into the bloodstream. If too much cortisol is released, that can lead to overeating, and weight gain especially in the midsection.6 Cortisol has a direct interplay with other hormones related to weight, sleep, and feeling of mood. While some of the weight gains might be due to ‘stress eating,’ cortisol will cause weight gain if too high. High cortisol is also linked to depression, food addiction, and sugar cravings.14
While meditation and exercise are great ways to reduce stress, sleep is also critical for stress reduction. If sleep is disrupted, like when night sweats occur, cortisol levels shoot up. HRT has been shown to reduce night sweats more effectively than any other treatment.
High levels of cortisol will deplete the ‘happy brain chemicals’ (serotonin and dopamine) leading to depression or mood swings. People with depression often have very high cortisol.14
High cortisol levels can increase food intake and promote weight gain. Eating a balanced diet, managing stress, and sleeping at least 7 hours per night can help normalize cortisol production.
Say goodbye to hormonal weight gain.
Hormonal weight gain is a struggle that very few talk about, but the conversation needs to happen. There are effective ways to adjust back to your natural balance. When hormones are in balance, women look and feel their best. But when hormones are imbalanced, a range of symptoms that include fatigue, sugar cravings, weight loss resistance, bloating, belly fat, trouble sleeping, anxiety or irritability, and constant stress are just the beginning.
Some companies charge high fees for unnecessary blood, urine, or saliva testing. The tests are completely unreliable, just like the levels of your menopausal hormones from day today. We know that hormones are too low at menopause, we know from symptoms how far off the levels are and can prescribe HRT without the need to test the levels of depleted hormones. The weight gain caused by hormones is treatable.
Hormones levels decrease with age, and doctors running panels won’t change that. Individual numbers on a hormone panel won’t achieve balance. Without balance, a woman can experience menopausal symptoms that are life-changing, even if her numbers appeared to be normal otherwise.
Winona offers our female patients a unique experience. Winona’s healthcare platform is a place to safely connect with a healthcare provider to receive care, to ask the sometimes difficult and maybe even embarrassing questions. Winona is not just a site to get a quick prescription. The decision to treat and whether to prescribe a product available through Winona is up to the patient and their Winona affiliated providers who are all licensed, board-certified, and never financially motivated to prescribe.
Winona is proud of our doctors, providers, and scientists who work tirelessly to treat all of the symptoms of menopause in the most effective way. That treatment might be a prescription or it could be one of our many over-the-counter treatments, but it will be the treatment that the patient and their doctor devise together.
Winona is open 24/7 for our female patients who are suffering from peri or menopausal symptoms. We pride ourselves in our service to our patients and never want to break physician-patient trust.
“This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.”
Glaser, Rebecca and Dimitrakakis, Constantine, “Testosterone Therapy in Women: Myths and Misconceptions.” Maturitas, Vol 74, issue 3, 2013, 230-234
3. Davison, S.L., et. al, “Androgen Levels in Adult Females: Changes with Age, Menopause, and Oophorectomy.” The Journal of Clinical Endocrinology & Metabolism, Vol 90, Issue 7, 2005, 3847-3853