MCT + Chili Make a Pretty HOT Pair: 50% Increase in Diet Induced Thermogenesis in Well-Controlled Human Trial

If you like chili oil, go for it, otherwise perform the reality check before ruining your taste-buds.

While the word "thermogenic" still carries much weight in the world of the average fitness maniac, SuppVersity readers like yourself should know better than to go crazy over rodent study #1021412 showing "potent thermogenic effects" when an extract from an exotic herb in Dr. Oz garden was administered once in an equivalent dosage that would require you to ingest the whole package of the corresponding "brand new, revolutionary" fat burner that's marketed by the said study.

Human study + no exotic herbs - so does it work?

Well with the study at hand, things are somewhat different. Firstly, the experiment Miriam E. Clegg, Mana Golsorkhi and C. Jeya Henry conducted was done with human, not rodent "subjects". Secondly, the "supplements" they used were no exotic herbs from Dr. Oz Garden or whatever remote region in the Himalaya they were simple MCT oil & Chilis - 20g of 30g of a hot chilli spice blend (Gourmet garden, Northampton, UK), to be precise the former and 30g of. And thirdly, the a +50% increase in diet induced thermogensis could actually make a difference - in the very long term and if you are using it on top of a energy restricted diet.

Figure 1: Macronutrient composition of the iso-caloric test meals; *due to the lower energy density of long-chain triglycerides, only 18.4 g of sunflower oil was used to match the energy content of the meals (Clegg. 2013)

In a randomized controlled fashion, the subjects, 7 healthy volunteers (6f 1m; 25.7±3.6 year;
1.69±0.09 m; 62.5±7.5 kg) who had reported fasted to the lag in the morning of the testing days, consumed a standardized English breakfast consisting of  consisting of an egg omelet, tomato, mushroom, sausage, bacon, toast and some "good old" orange juice.

Suggested read: "Capsaicin - 2.56mg to Keep Your Metabolism Running on a Diet. Cold Thermogenesis - 5°C for 6kcal/h. Mobile Phones - 0.853 W/kg Pulsed EMR to Mess Up Neuro-transmitters" | read more

"The cooked breakfast was prepared with chilli and MCT oil, chilli and sunflower oil, bell pepper and sunflower or bell pepper and MCT oil added to the omelet.

Glucose was added to chopped bell pepper to give it a similar macronutrient and energy cost as the chilli mix. The chilli mix consisted of 60 % chilli (cayenne, habanero). The capsaicin content of the chilli blend was estimated about 2,000 ppm capsaicin (based on information provided by the manufacturers). According to this, the 30 g chilli blend added to breakfast meal was comparable to the amount of chilli used (30 g) in earlier studies to assess the effect of chilli on metabolic parameters." (Clegg. 2013)

The resting metabolic rate of the subjects had been deterimned before breakfast, while the diet induced thermogenesis (DIT) was quantified for 15 minutes they "broke their fast" (learn more about "breaking the fast" here) and then every 30 min within the following 6h.

Suggested read: "Are You Still Burning Calories or Already Losing Fat? Study Shows: 5x15 Min HIIT Reduce Body Fat & Improve Fitness Twice as Effectively as 5x40min of Classic Cardio" | read more

"The energy expenditure increased postprandially following all four breakfasts reaching a peak in the chilli–sunflower oil and pepper–sunflower oil at 1 h and at 2 h in the chilli– MCT oil and pepper–MCT oil, respectively. [...]

There were significant differences in total DIT and percentage DIT between the different breakfast meals (P=0.003). [...]

Chilli–MCT had the highest EE, and pepper–sunflower oil had the lowest. It was noted that the increased energy expenditure occurred between 2 and 6 h postprandially; analysis of these data alone substantiated the results above.

Interestingly, the rate of fatty acid oxidation did not vary significantly. Well, with one exception: The difference between the contribution of fats to the total energy expenditure was significantly different for the pepper–sunflower oil and pepper–MCT oil (P=0.032) trials. Similarly, the meal induced elevation in carbohydrate expenditure was more pronounced in the +MCT trials than in the + sunflower oil trials, but neither of these effects resulted in measurable differences in terms of satiety, hunger, fulness or prospective food consumption, which were all identical across the groups.

Real-world Significance and the Theory of Relativity

The same goes for symptoms of gastrointestinal distress, which is something that's actually a little surprising. After all, both MCTs and chili have been described as potential gut irritants in certain populations, yet none of the participants appeared to suffer more during the corresponding testing conditions.

Figure 2: Ratios are important, but total increases in energy expenditure of max. 12kcal are simply laughable (Clegg. 2013)

So, we do have a side-effect 50% increase in diet-induced thermogenesis? Awesome... well, you look at the absolute value of post-prandial energy "wasting" in response to the selection of the "right" oils and take into consideration that a previous study showed that the "fatty oxidation bonus" from MCTs vanish over time (learn more), it remains questionable, whether even these, allegedly pronounced increases in diet-induced thermogenesis will do anything.

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Remember: "The only consistent finding among [fat loss trials on both ends of the low vs. high carb spectrum] is that adherence - the degree to which participants continued in the program or met program goals for diet and physical activity - was most strongly associated with weight loss." (Pagato. 2013)

Bottom line: Personally, I don't think it's worth to spice up your food with "MCT + chili" - unless, of course, you like it this way. If that's the case the extra 12kcal of energy expenditure are something I believe few of you will mind.

If, on the other hand, you are just telling yourself that you like your food with chili and MCTs, you should not be wondering that all your past weight loss efforts have sucked. If there is anything that really messes with weight loss success, it's not low postprandial thermogenesis, but not sticking to one's diet; and if the food you eat does not only contain less energy than you want, but also tastes like fiery crap, falling off the wagon and not achieving your fat loss goals is almost guaranteed; and if that happens your relatively large (~50%), but in absolute terms already irrelevant increase in daily energy expenditure is not going to help you.

References:

• Clegg ME, Golsorkhi M, Henry CJ. Combined medium-chain triglyceride and chilli feeding increases diet-induced thermogenesis in normal-weight humans. Eur J Nutr. 2013 Sep;52(6):1579-85.
• Pagato SL, Appelhans BM. A Call for an End to the Diet Debates. JAMA. 2013;310(7):687-688.

Long Chain Triglyceride Feeding Reduces Exercise Performance by >55% - Cambridge Scientists Find Reduced Mitochondrial Efficiacy in Rat Hearts.

Image 1: The ketogenic diet is also
referred to as the long chain
triglyceride diet by some dieticians
(image from fingercandymedia.com)

In view of the current low-carb hype, people tend to forget that, after all, carbohydrate consumption has been shown time and again to improve the performance of endurance athletes. And despite the existence of a few studies about "fat adaption" which report equal or even improved endurance performance in athletes on low carb diets, previous findings of Murray and his colleagues from the Department of Physiology, at the University of Cambridge clearly showed detrimental effects of short term high fat feeding (9 days) on the exercise capacity of rats. These results are corroborated by findings of Holloway et al. (Holloway. 2011) who found cardiac high-energy phosphate metabolism and cognitive function to be impaired in healthy human subjects on a high-fat diet. Now, it is quite obvious that these findings stand in contrast to all the beneficial effects about which you have read at the SuppVersity and even much more mainstream scientific webpages, such as Science-Daily, lately. Well, I guess this makes the results of Murray et al.'s latest study particularly interesting (Murray. 2011b).

Illustration 1: Study design.

In order to find out what the differential effects of medium and long chain triglyceride feeding on rats were the scientists allocated 33 rats to one out of six groups (cf. illustration 1), of which three were allowed to live a lazy rat-life, while the other three groups (the exercise groups)

... were habituated to a motorised treadmill (Columbus Instruments, OH, USA) over a 14 day period, running at gradually increasing belt velocities

until the rats were "proficient at running on the treadmill for 5 min at a velocity of 10 m/min on a 5° incline". And while I do not think you would call running on a 5° incline at a speed of 10m/min (=0.6km/h or 0.37miles/h) exactly "athletic" in human terms, this was only the initial speed the treadmill was set to in the exercise tests in the course of which the speed was increased by an additional 1 m/min with each minute until the rat fatigued.

Other than one may have expected, none of the fat-feedings induced significant changes in body weight in the sedentary rats, when compared to their chow fat controls (cf. figure 1). The +59% increase in visceral (epididymal) fat, the LCT fed rats experienced, is however a clear marker of impeding metabolic derangement and indicates, in the presence of otherwise unchanged bodyweight, a significant loss of lean body mass in the long chain triglyceride fed rats.

Figure 1: Selected biomarkers of sedentary and exercised rats after 15 days of standard chow, high medium chain triglyceride or high long chain triglyceride diet in comparison to chow fat, non-exercised control
(data calculated based on Murray. 2011b)

In the exercised rats, on the other hand, medium chain triglyceride feeding had quite similar effects (+44% vs. sedentary chow fat control), although the shorter MCTs did not exert any significant detrimental effect on the exercise capacity of the rats.

Image 2: Current research
suggests that MCT oils are
probably not useful to athletes
who are not on a very low
carbohydrate diet. The replacement
of long chain with these shorter
chain triglycerides, on the other
hand, could make sense from a
performance point of view

Medium Chain Triglycerides, the performance fats? While there was no decrease in performance observed in the MCT group in the study at hand, the performance increase some supplement companies will promise in order to sell their MCT oils and/or MCT-enriched supplements, was non-existent as well. In this regard, Murray et al. remark that

[i]t has been theorised that MCT-rich diets might improve energy utilisation during exercise, perhaps through increased ketogenesis, however there is little conclusive evidence for this.

Interestingly, one study that is often cited in this context (Fushiki. 1996) in which the swimming endurance capacity of mice fed an MCT-rich diet over 6 weeks increased, used a LCT-fed mice as controls. In view of the results of the study at hand, this "ergogenic effect" of MCTs has to be reevaluated. It is in fact much more likely that MCT-fed rats just avoided the detrimental effect of the LCT diet.

So what does all that go to say for you, as an active or even athletic human being who is trying to find the appropriate and delicate balance between health, looks and performance? A fundamentally important observation was made in this context by the same group of Cambridge scientists a few month before (Murray. 2011a), when they found that endurance exercise training blunts the deleterious effect of high-fat feeding on whole-body energy efficiency and mitochondrial respiration - much to the scientists surprise highly trained endurance athletes appeared to even thrive on the "bad" high fat diet.This is an observation I would attribute to what I initially referred to as "fat adaption", i.e. an improvement in both rate and energy efficacy of fatty acid oxidation in a group of people whose bodies are used to literally "run out of carbs", no matter how many energy gels they are consuming in the course of a competition.

With regard to the fatty acid specific differences Murray et al. observed, one could speculate that in an intermediate phase, i.e. for example in the first 2 weeks of low-carb dieting, where most dieters complain about low energy levels, brain fog and other symptoms of suboptimal energy metabolism, the use of MCTs to provide "carb-like instant energy" could provide an adequate strategy to bridge the time-gap your body needs to ramp up mitochondrial fatty acid oxidation in order to fuel your metabolic demands from dietary fats, alone.

If you have read the Amino Acids for Super Humans write-up on l-carnitine, you are probably already aware that supplementation with L-3-hydroxy-4-N,N,N-trimethylaminobutyric acid (l-carnitine) could help to speed up / sustain your ability to use (long chain) triglycerides as fuel by shuttling the fatty acids into and (this is commonly overlooked) out of your cellular power plants (if you want to know more about LCAR, ALCAR, LCLT & co, read Part IV of the Amino Acids for Super Humans Series).

That being said, it would be interesting to see a similar LCT feeding study with appropriate adaptation times in order to decide whether the rats just were not accustomed or generally unable to efficiently metabolize the long chain triglycerides and to access what the long-term consequences of the upregulation of PPAR-gamma and UCP3 in the heart muscle will look like. I'll keep you updated!

Ketogenic Dieting and Vitamin & Mineral Imbalances!? Differential Effects of Classical Ketogenic and Medium Chain Triglyceride Ketogenic Diet on Vitamin and Mineral Status in Children

"Keto diets are unhealthy! You simply do not get enough quality nutrients if you do not eat your healthy pasta, bread and other starchy carbs." I suppose many of you - just like me - cannot tolerate the black-and-white thinking of either of the two, the high or the low/no carb camp and are thus as interested in the recently published results from a 12 month dietary intervention using either a classical ketogenic diet (Christodoulides. 2011), which uses long chain triglycerides as its primary source of fatty acids, or a medium chain triglyceride ketogenic diet, where the majority of fatty acids came from MCT oils [unfortunately the scientists used Liquigen or MCT oil (both SHS International) instead of a natural source of MCTs, like coconut oil] on vitamin and mineral status of 49 children (age 2-16 years).

Although the results are somewhat skewed due to the extensive use of supplements - apart from the MCT oil in the MCT group, all children received an additional mulit vitamin [either Forceval Junior capsules (Unigreg, Morden, UK) or Phlexy-vits powder sachets (SHS International)], the results (cf. figure 1) suggest that, after all, ketogenic dieting cannot be that detrimental to you vitamin and mineral status as one might expect.

Figure 1: Effects of 12 month on classical or MCT based ketogenic diet on vitamin and mineral status in 49 children.
(data adapted from Christodoulides. 2011)

It is particularly interesting that while vitamin E increased dramatically in the long-chain fatty acid fed "classical keto" group (no wonder in view of the amount of vitamin E present in most long-chain seed oils), the vitamin A level in that group dropped similarly dramatically.

In comparison, the changes in Zinc, Selenium and Magnesium appear to be negligible. In the case of magnesium the observation that

the pairwise comparison with baseline in children who provided data at both time points showed a significant decrease at 3 and 6 months and a highly significant decrease [of magnesium levels] at 12 months

especially in the classical diet is a cause of concern for "those using the diet to treat children with intractable epilepsy", where low(er) magnesium levels appear to correlate with seizures and magnesium supplementation is used as part of the common treatment strategy.

I leave it up to you to decide, whether your think that either a classical or, let alone, a MCT based (with MCTs from supplements instead of whole food sources) diet can be more than a temporary intervention or treatment strategy. Despite the positive evidence that you won't die from mineral insufficiencies or vitamin deficiencies within 12 month of vitamin and mineral supplemented (I assume every keto dieter will take a good multi vitamin anyway) ketogenic dieting, I am still not even remotely considering this to be an option for me.

True or False? Caffeine is The Main Main Stroke Protectant in Tea & Coffee. High MCT Diets Are the Key to Longterm Fat Loss. Soybean Oil Makes You Fat not Heavy.

Adelfo Cerame Jr. after winning his weight class, the overall and the pro-card (leave him a message).

The first "True or False?" today, does not really pertain to diet and nutrition science, but it is still highly relevant for the SuppVersity:

Adelfo Cerame Jr. did eventually win his well deserved pro-card at the Wheelchair Nationals in Florida, yesterday. - True!

Ok, I have to admit that this may have been too easy with the picture of Adelfo holding the trophies for his weight class and the overall in his hands on the right, but it was the best way to include this important news "seamlessly" *rofl* into today's SuppVersity article.

You want some more difficult stuff? Well, let's see what you know about tea, coffee, MCTs and heated soy bean oil, then.

Caffeine (probably) is the main stroke protectant in coffee and tea

True. As a recent study from the Universidade Federal de Santa Maria in Brazil clearly indicates, the "bad" caffeine is at least one, if not the main anti-oxidants that's responsible for the neuroprotective effects of coffee, tea and co (Souza. 2013).

Caffeine is also part of the classic CCC fat loss stack (learn more)

According to the results of the paper MA Souza et al. are about to publish in one of the future issues of  Neurochemistry International, a 2-weeks front-load with 6mg/kg caffeine per day increases the glutathione (=master antioxidant of the mammalian body) levels in the brain and protects rats from the oxidative damage and subsequent seizures in response to the administration of pentylenetetrazol-induced seizures (pentylenetetrazol is a circulatory and respiratory stimulant that overtaxes the brain, when it is administered in high doses).

What you should keep in mind, though, is the fact that Souza et al. used a dosage that was way lower than the amount of caffeine the average stim-junkie is consuming. It is thus not unlikely (in fact it is quite the opposite ;-) that we are dealing with a hormetic effect that occurs at human equivalent doses of 0.97mg/kg (~1 small cup of coffee) and turn against you when you escalate the doses to four or five MonterBullDrinks(TM) per day... I mean, the mere willingness of spending money on products like this goes to show you that drinking them compromises people's brain function, doesn't it? No, well I guess you have to reread the "Fat Content Per Energy Drink 0g. Fat Gain Per Energy Drink Drink 18g Study", then (reread it).

Most recent epidemiological human data supports these findings

And in case you don't believe this was relevant, check out the latest study in Stroke, in which Kokubo et al. which does not only confirm the stroke protective effects of green tea and coffee (Kokubo. 2013), but also yields some insights into what may be the "optimal" intake. After all, it takes 2x more green tea to achieve the effect you get from >2x cups of coffee per day, which is another hint at caffeine as the major driving force behind the anti-stroke effects of tea and coffee. Why? Well a large cup of Starbucks' green tea has 80mg of caffeine, the same amount of their regular coffee has roughly 290mg of caffeine in it.

Figure 1: Age and multivariable-adjusted hazard ratios of cardiovascular disease and its subtypes according to coffee (left) and green tea consumption in 82 369 Japanese (aged 45-74 years; without cardiovascular disease [CVD] or cancer in 1995 and 1998 for Cohort I and II, respectively) who received 13 years of mean follow-up through the end of 2007 (Kokubo. 2013)

Yet despite the validity of the "more caffeine = more brain protection" eqation the catecholamine surge of high amounts of green tea, but even more so coffee is not what you would call "heart healthy" (see figure 1; I would love to tell you the caffeine equivalents, but the scientist don't disclose the serving size). Just another reason to take it easy on stims in pill and drink form and keep your daily caffeine intake in the < 400 mg range (suggested read especially for the smokers: "Putting an "N" as in "nicotine" into "EC" amplifies the negative effects of ephedrine and caffeine on your heart";  read more)

Eating tons of medium chain triglycerides (MCTs) will make you lean

Are we, or rather you, my American friend eating too much fat or simply the wrong type of fats? According to a study that was in the SuppVersity news in Nov. 2012, it's the latter the "SAD Diet Has the Optimal Ratio to Induce Diabesity" (learn more)

It depends. While it may be that you can derive certain benefits by kicking out junkfood from your diet and replacing it with MCTs the "fat-burning" effects of medium chain triglycerides (MCTs) wear off after one to two weeks (White. 1999). Unfortunately, this is way longer than the usually cited studies on the direct metabolic effects lasted, so that a cursory look at the research easily fools you to believe that you could effectively burn fat by simply using MCT oils instead of whatever "bad" fat you had been using before.

Moreover, in the aforementioned study that was published in the American Jorunal of Nutrition roughly 14 years ago the postprandial total energy expenditure was already only 3% higher after the MCT meal in the first week. And it's not only that this advantage disappeared within the next 7 days, the respiratory ratio, a measure of the ratio of carbohydrate to fat oxidation, total fatty acid oxidation and carbohydrate oxidation were also identical in the  32% MCT and 32% LCT diets (both diets contained additional 8% of fat from other sources).

But what about all the other research?

While the transient benefits of the MCT feeding on energy expenditure alone are unlikely to have practical relevance there are a good handful of trials, which show some real world benefits in various dieting scenarios. Unfortunately, they are usually too short (Alexandrou. 2007), compare MCTs to beef tallow & co only diets, observe increases in fatty oxidation, which don't translate into changes in body composition (St-Onge. 2003), or have the subjects in the control group use relatively fragile control oils, such as olive oil for frying and cooking (St-Onge. 2008).

Accordingly, you should not be too surprised that the latest review of the effects of dietary intake of medium chain triglycerides on body composition, energy expenditure and satiety concludes: "

Curried Carrot Soup w/ coconut oil certainly qualifies as a good food choice, also bc. it's made with coconut oil, not plain MCTs (more).

"In the present review it was possible to verify that data related to increased satiety after consumption of MCT are quite controversial. Most studies showed no significant difference as to increased satiety and/or satiation related to lipid consumption. [...] A relevant fact in the lack of consensus among the studies concerns the large variation in the amount of MCT provided in different studies due to lack of reference values for a minimum, ideal and maximum consumption in literature. Moreover, there isn’t enough to long-term studies to identify either beneficial effects or potential harmful effects." (Souza. 2013)

If you go through the list of studies included in the review there are a couple other interesting patterns emerging: (a) the effects - if there were any - originated from the gut (mostly greater satiety effects), (b) if there were effects on body composition those often reached statistical significance in the obese individuals, only, (c) the benefits were more pronounced the less the subjects ate (esp. on those 800kcal hunger diets), (d) when the control was not nasty corn oil, or saturated long chain triglycerides (Atkins diet style), the effects were non-existent.

So, if your are lean, your current diet is balanced and your main fat source is neither corn oil nor beef tallow, the chances that you will be better off with expensive MCT oils than with a couple of spoons of coconut oil in your diet probably border zero. You see, it's just as so often not so much about "adding something in", as it is about leaving something else out / replacing it with a better food choice.

Soy bean oil offers a shortcut to metabolic disease even in the absence of obesity

True. I guess that this "true or false" item was actually way too easy to answer, but the recently published study by Potu et al. is simply too intriguing not to add it to the huge heap of existing evidence that the overabundance of "healthy" polyunsaturated fats from purportedly healthy plant oils is a major contributer to the fat mess we are dealing with.

Figure 2: Effects of 16 weeks on non-heated and heated soybean oil diets rodent food intake, weight gain and body fat (EWAT & IWAT) levels (Penumetcha. 2013)

Now, pro-obesity and pro-diabetic effects of corn oil, soy oil & co are actually no news. Penumetcha et al. do yet emphasize that they are the first to observe that soybean oil which has been heated on a hot plate at 190°C for 3 hours (think of the huge pots, frying pans & co that are used to produce convenient and fast foods) before it was added to the rodent chow has the unique ability to increase its consumers body fat levels without increasing their total body weight. Excellent, right?

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Thats it for today! Ok, I guess that was too easy, as well. Still, it's true and I hope you enjoyed the last week and are already looking forward to the next week of exercise and nutrition science news here at the SuppVersity.

In the mean time you can kill some time by surfing over to the Suppversity Facebook Wall, where you will find news such as

• 

  Even if you align them like that, it is at least debatable whether capped fish oil is much more natural than the structurally modified 16 -carbon saturated fatty acid tetradecylthioacetic acid (TTA). And the usefulness of the longterm use of both remains questionable (learn more). 

  Beware of omega-3s unless you have the right genes -- New Inuit study confirms: If n-3 fatty acids are good or bad for you is in your genes (read more)

• Muscular imbalances commonly overlooked factor in lower extremity sports injuries -- Scientists observe significant relationship of the coordination between muscle strength (ankle plantar flexor/ dorsi flexor), (hip addactor/abdactor), (knee flexor/ extensor) with muscle injuries (read more)

• Arteriosclerosis is not a "neolithic" disease that occurred with the advent of agriculture -- Lancet paper debunks the myth of the "agricultural origin" of atherosclerosis (read more)

and when you are at it, don't forget to congratulate the one and only Adelfo Cerame Jr for finally bringing home those two small muscular statues you see in the image on the top of the page.

References:

• Alexandrou E, Herzberg GR, White MD. High-level medium-chain triglyceride feeding and energy expenditure in normal-weight women. Can J Physiol Pharmacol. 2007 May;85(5):507-13.
• Kokubo Y, Iso H, Saito I, Yamagishi K, Yatsuya H, Ishihara J, Inoue M, Tsugane S. The Impact of Green Tea and Coffee Consumption on the Reduced Risk of Stroke Incidence in Japanese Population: The Japan Public Health Center-Based Study Cohort. Stroke. 2013 Mar 14.
• Rego Costa AC, Rosado EL, Soares-Mota M. Influence of the dietary intake of medium chain triglycerides on body composition, energy expenditure and satiety: a systematic review. Nutr Hosp. 2012 Jan-Feb;27(1):103-8. 
• Souza MA, Mota BC, Gerbatin RR, Rodrigues FS, Castro M, Fighera MR, Royes LF. Antioxidant activity elicited by low dose of caffeine attenuates pentylenetetrazol-induced seizures and oxidative damage in rats. Neurochem Int. 2013 Feb 26.
• St-Onge MP, Bourque C, Jones PJ, Ross R, Parsons WE. Medium- versus long-chain triglycerides for 27 days increases fat oxidation and energy expenditure without resulting in changes in body composition in overweight women. Int J Obes Relat Metab Disord. 2003 Jan;27(1):95-102.
• St-Onge MP, Bosarge A. Weight-loss diet that includes consumption of medium-chain triacylglycerol oil leads to a greater rate of weight and fat mass loss than does olive oil. Am J Clin Nutr. 2008 Mar;87(3):621-6.
• White MD, Papamandjaris AA, Jones PJ. Enhanced postprandial energy expenditure with medium-chain fatty acid feeding is attenuated after 14 d in premenopausal women. Am J Clin Nutr. 1999 May;69(5):883-9.