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| Super Moderator Geregistreerd: Apr 2002 Locatie: افغانستان Geslacht: V
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Karma Power: 30 | Impact of the menstrual cycle on determinants of energy balance:
Impact of the menstrual cycle on determinants of energy balance: a putative role in weight loss attempts. L Davidsen et. al. - International Journal of Obesity (2007) 31, 887-890 Abstract: Women's weight and body composition is significantly influenced by the female sex-steroid hormones. Levels of these hormones fluctuate in a defined manner throughout the menstrual cycle and interact to modulate energy homeostasis. This paper reviews the scientific literature on the relationship between hormonal changes across the menstrual cycle and components of energy balance, with the aim of clarifying whether this influences weight loss in women. In the luteal phase of the menstrual cycle it appears that women's energy intake and energy expenditure are increased and they experience more frequent cravings for foods, particularly those high in carbohydrate and fat, than during the follicular phase. This suggests that the potential of the underlying physiology related to each phase of the menstrual cycle may be worth considering as an element in strategies to optimize weight loss. Studies are needed to assess the weight loss outcome of tailoring dietary recommendations and the degree of energy restriction to each menstrual phase throughout a weight management program, taking these preliminary findings into account. comments (Lyle McDonald): Compared to men, women get the short end of the stick in almost everything related to body composition. Their bodies fight back harder, they lose both weight and fat slower, they gain muscle more slowly, etc. There are a lot of potential reasons for all of this and it's been theorized that the importance of women in keeping humanity alive (by raising children) during famines is a huge part of the gender discrepancy. Women are more likely to be in the super-obese category and far more likely to survive famines than men. Their bodies are calorie storing machines which tend to fight back all interventions to take the weight/fat off. I addressed this topic in somewhat more detail in my booklet Bromocriptine. Of course, the biggest potential impact on all of this is hormones which differ drastically between men and women. It's been known for a while that women's fuel utilization changes during their menstrual cycle, as does appetite and potentially energy expenditure. It's been suggested that dieting (and training) might or should be modified during the menstrual cycle to match up physiologically with what is going on in a woman's body; I'll come back to this a bit below. This week's study reviews all of that information as well as the impact of birth control on bodyweight; finally it makes some suggestions as to how this might be applied practically. The first section of the paper is simply a review of the hormonal changes which occur during a normal menstrual cycle. Although there is variability, the typical woman's full cycle is 28 days (this is an average) which is typically divided up into 4 distinct phases. With menstruation taken as day 1, we can define early follicular phase (day 1-4), late follicular (days 5-11), periovulation (day 12-15), and luteal phase (days 16-28). A number of hormones change during the cycle but the two that I'm going to focus on are estrogen and progesterone. During the early follicular phase, both estrogen and progesterone are relatively low. Estrogen shows a peak in the late follicular phase followed by a drop. Progesterone starts a slow increase through ovulation and both estrogen/progesterone peak in the middle of the luteal phase before returning to baseline. The paper notes that body temperature typically goes up after ovulation, remains high during the luteal phase before returning to baseline at or after the start of menstruation. The next section of the paper examines research on energy intake during different parts of the menstrual cycle. In animals, energy intake is reduced at ovulation (when estrogen peaks) and increases after ovulation when progesterone is peaking; this has long been interpreted as indicating that progesterone drove food intake. Research in humans has generally borne out that pattern, higher energy intakes during the luteal phase and lower intakes during the follicular phase; the increase has generally been reported to be between 90-500 calories day. It's interesting to note that some research suggests that it is falling estrogen rather than increasing progesterone that drives hunger; there is also some reason to think that it's a combination effect of estrogen and progesterone that is having the overall effect. Tangentially, the paper mentions that estrogens (which may inhibit food intake) might play an important role for weight loss. I bring this up for a couple of reasons. It's interesting to note that with increasing fat loss, estrogen levels typically drop, this is probably part of what drives hunger in women. Also, women trying to deliberately banish estrogen while dieting may be doing themselves more harm than good (I'd also note that some research suggests that estrogen may be lipolytic and improve leptin sensitivity, both of which would HELP while dieting). Finally, the paper notes that some of the drive for appetite may be mediated by changes in blood glucose homeostasis. Empirically, some women seem to be more prone to hypoglycemia during certain phases of the menstrual cycle and this would tend to drive hunger. Ensuring that blood glucose levels stay stable might be extremely beneficial during those periods. The next part of the paper examines changes in macronutrient intake, food cravings and PMS. Studies, as usual, are inconsistent showing increases in carb, fat and protein intake during the luteal phase. Some of this may simply be related to being hungrier in general. Some research has indicated that the increase in carbohydrate intake is due to a craving although, with chocolate being the most craved item, other possibilities exist. Cravings for a sugar/fat combo or something else entirely may be at large (i.e. some research indicates that magnesium supplements help with PMS related cravings and chocolate tends to be high in magnesium; women may simply be self-medicating an important micronutrient). Next, the paper looks at the impact of menstrual cycle on energy expenditure (this brings us back to the increased body temperature I noted above). The major increase in energy expenditure occurs also during the luteal phase (when hunger is increased) with increases of 2.5-11.5% having been reported; I'd note that this only amounts to a daily increase in energy expenditure of 90-280 calories per day. That would be contrasted to the potential increase in appetite of 90-500 calories. That is, while energy expenditure is up during the luteal phase, so is appetite; increases in energy intake can easily overwhelm the small increase in energy output. The increase in metabolic rate is thought to be primarily related to the increasing progesterone levels. So while increasing progesterone may not be driving the increased appetite, it may be stimulating metabolic rate slightly during the luteal phase. Next, the study examined the impact of birth control pills on bodyweight, first pointing out that there a number of different types of birth control containing synthetic estrogen, progesterone or possibly both. Studies have examined the impact of birth control on energy intake and several find an increase in both total energy intake and fat intake; others have found no effect. With limited research it's hard to tell if this is an issue of different types of birth control or possibly individual variance; empirically women seem to respond massively differently to birth control. Some go crazy, some get suicidal, some gain weight, some don't. As far as energy expenditure, while one study showed a small increase in basal metabolic rate of 5%, others have found no effect. Again, type of pill and individual variance is probably at play here. Looking at bodyweight, most studies have apparently reported no substantial change in bodyweight with birth control pills although many show a trend towards increased bodyweight. One exception is Depo-Provera injections which are associated with weight gain. Finally the paper looks at potential implications for dieting and weight loss. The paper argues that considering which phase of the menstrual cycle the female in when starting a diet may be important. They argue that starting the diet premenstrually when hunger and food cravings are most intense may be a bad idea, starting a diet following menstruation or in the late follicular phase when food cravings and hunger are less may make compliance easier. They suggest that increasing total energy intake 5-8 days before menstruation (when hunger/energy expenditure are at their highest) may prevent a suboptimal caloric intake. I'd argue that, in theory at least, keeping calories under control when energy expenditure is up for hormonal reasons may be superior. Of course, that also means keeping calories down when hunger is at its worst. The paper also argues that as chocolate is seemingly irreplaceable due to cravings, small amounts of dark chocolate should be allowed to improve dietary adherence. Interestingly, I first read that idea in an older book called "Why Women Need Chocolate" which was an interesting look at food cravings. Given that I wrote a book about flexible dieting and allowing flexibility in dieting to improve adherence, I think there is a lot of logic in their argument (whether or not chocolate is truly irreplaceable is arguable in my mind, simply ensuring sufficient magnesium seems to help many women with cravings). At the end of the day, better to allow a small controlled amount of chocolate than feel deprived and end up eating the entire bag. An extra 100 calories is always better than an extra 1000 calories.
__________________ As you are now, I once was. As I am now, you'll never be ©3XL ®2000 The only easy day was yesterday...............Life is hard, so am I Geloof niets, probeer alles |
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| Massive Warrior Geregistreerd: Jun 2005 Locatie: ♥♥-NL-♥♥ Geslacht: M
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Karma Power: 60 ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() | Re: Impact of the menstrual cycle on determinants of energy balance:
Citaat:
ik zal even wat kromme zinnen er uit halen anders
__________________ Sticky: Trainingsmethodes Plan voor Gewichtstoename + krachtvoeding! TVDW: Benen trainen! Sticky: tienerbodybuilding Laatst aangepast door SHUTTERSPEED : 11 October 2007 om 20:27. | |
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| | #3 |
| Cool Novice | Re: Impact of the menstrual cycle on determinants of energy balance:
Ik zit er al een poosje aan te denken om mijn voeding te laten fluctueren met de cyclus. Sowieso eet ik wat meet vet in week 4 om menstruatieklachten te voorkomen en ik heb generkt dat mijn insulinegevoeligheid in week 1 en 2 veel groter is dan na de ovulatie. Uit dit artikel blijkt dat week 3 en 4 een mooie tijd zijn om vet te verliezen. Ik denk dat week 1 en 2 weer beter zijn voor de opbouw van spieren omdat dan zowel estrogeen als testosteron hoog liggen.
__________________ A tigress in a butterfly suit. |
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