New Leptin Study

S

Steve McDermott

New Member
I was looking at the Harvard Medical School newsletter (Focus) the other day and what is on the front page? "Leptin Serves Body as Energy Signal. Study confirms in humans that the hormone helps regulate reproduction. Much of the research on leptin has been done on obese people in the fed state. This study looked at leptin levels in starvation conditions. This is much more relevant to what bodybuilders do while dieting.

The study, which will be in the May 1st Journal of Clinical Investigation involved 8 healthy men. They spent four, five day sessions in the hospitals research center. They first were fed a maintenance level diet to determine baseline hormone levels. Then during the next three visits they spent 3 of the 5 days fasting. At the second visit they were injected with a plecebo and at the third they were injected with low doses of leptin. At the final visit they were injected with enough leptin to restore levels to baseline. During the experiment blood was drawn every 15 minutes (even while asleep) to monitor hormone fluctuations.

During the starvation periods testosterone levels droped significantly along with a drop in leptin (expected). When leptin was returned to normal levels via injection, testosterone levels returned fully to baseline. This clearly showed that leptin has a direct effect on the HPTA. The study also showed a relationship between leptin and the The thyroid hormones. Replacing leptin also had a mild effect on IGF1 levels. It had no effect on growth hormone or cortisol levels.

This was very interesting to me in that when dieting with refeeds, I have found that I can add small amounts of muscle (given that the refeeds are adequate enough to boost leptin signigicantly). I also have noticed that dieting without refeeds has not yielded similar results. It also makes sense that in times of starvation that the body switches its focus from reproduction to survival.
 
[b said:
Quote[/b] ](given that the refeeds are adequate enough to boost leptin signigicantly)
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do you mean that refeeds can boost leptin levels statistically significantly, or boost levels alot? a minute unimportant rise in leptin that makes no difference to the body can still be statistically significant....
im really curious.
 
I meant it in a physiological sense. If the refeed is done properly and long enough (not sure how long is optimal), it should be enough to boost leptin levels enough to reverse some of the effects of harsh dieting. Of course you need to refeed often enough (based on current BF%) to reap these benefits.
 
I also recall this article associating leptin with fertility in rats.

Overeating for a period upwards of 5-6 hours will rise leptin, but proper upregulation requires something like 24 hours, at 25-50% above maintenance. The more difficult question is "how often". In general, the leaner you are the more frequently you need to refeed. When I was trying to get below 9%, I realized that I needed more than one refeed per week. The refeed should better have as little fat as possible.
 
[b said:
Quote[/b] (micmic @ May 09 2003,1:09)]The refeed should better have as little fat as possible.
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Agreed. I shoot for 10-15% of cals from mostly O3 fats during refeeds. It doesn't always happen that way but I'm usually close.
 
The actual amount of rise in leptin is relatively small, , even when starved and in small studies is relatively (statistically) insignificant in the most part. But personal and other experiences show that it makes a difference, at least when getting leaner than average.
 
Does anyone have any information (or links to good sites) about how the whole refeed thing whilst dieting is supposed to work.

What do i do between refeeds (how far below maintenance? what macronutrients?)

How big should a refeed be (again, what macronutrients?) and for how long? How often do i need to refeed?

Does any of this affect how i train or do cardio?

Sorry for all the questions, but ive heard refeeds mentioned quite a bit round here and would like to know more - thats what this forum is all about, right? :confused:

Thanks in advance

Paul
 
Cheers mic!

Edit:

I take it form reading them that you only need go hypocaloric for the dieting days, not necessarily ketogenic (it said macronutrient breakdown will not affect leptin levels so choose them to suit). Thats a very good thing for me as I was considering a full CKD but was concerned how the low carbs would affect my workouts (I dont fancy a full body 15RM workout on a friday after having no carbs for 5 days! )

From this it looks like i just need to go hypo/hypercaloric.

Does anyone think going hypocaloric during the week (but enough carbs to train ok) and refeeding at the weekends is a good option?

Ive worked out i need to go 2200 for hypo and about 4000 for the refeeds. Anything obviously wrong with this??

Thanks again...

Paul
 
Here is a short list of recommendations:

The fatter you are the less likely you are to lose muscle when dieting. As you grow leaner, your leptin levels fall and fat cells become more resistant to the idea of meeting all your energy needs themselves. This leaves muscle tissue more and more vulnerable to catabolism the leaner you get.

There are some small steps that a person can take to help to elevate leptin levels. The first thing is to cycle calories. Research has shown that short periods of carbohydrate refeeding temporarily elevate leptin levels. Keep in mind that fatter you are, the more leptin you have. This is because fat cells are acting as glands, being the primary source of leptin for the body. Not only that but a persons leptin levels are directly correlated to the amount of fat the carry.

So, periodic refeeding becomes more and more beneficial as you get leaner. As a guess I would say that if you are above 25% body fat, you don’t need to reefed. When you get down to 15% a 24 hour reefed done every two weeks may help you keep more muscle. Then once you hit 10% a weekly reefed is called for. Finally, once you get to about 6-8% a twice weekly refeed might be in order.

During refeeding it is important to keep fat low. Essential fats such as omega-3s and CLA should probably be the only “intentional” fat during the refeed.

Another thing we can do is to supplement with Zinc and Vitamin E. (1,2,3) Now this isn’t brain surgery, all you have to do is supplement with zinc and vitamin E. How much? Well, take 15-30mg zinc daily and about 400-800iu vitamin E is fine. I would also suggest glucosamine at about 1,000mg-2,000mg per day.(4,5,6,7)


1. Chen MD, Song YM, Lin PY. Zinc may be a mediator of leptin production in humans. Life Sci. 2000 Apr 21;66(22):2143-9.
2. Mantzoros CS, Prasad AS, Beck FW, Grabowski S, Kaplan J, Adair C, Brewer GJ. Zinc may regulate serum leptin concentrations in humans. J Am Coll Nutr. 1998 Jun;17(3):270-5.
3. Isermann B, Bierhaus A, Tritschler H, Ziegler R, Nawroth PP. alpha-Tocopherol induces leptin expression in healthy individuals and in vitro. Diabetes Care. 1999 Jul;22(7):1227-8.
4: Zhang P, Klenk ES, Lazzaro MA, Williams LB, Considine RV.
Hexosamines regulate leptin production in 3T3-L1 adipocytes through transcriptional mechanisms. Endocrinology. 2002 Jan;143(1):99-106.
5: Emilsson V, O'Dowd J, Nolan AL, Cawthorne MA.
Hexosamines and nutrient excess induce leptin production and leptin receptor activation in pancreatic islets and clonal beta-cells. Endocrinology. 2001 Oct;142(10):4414-9.
6: Considine RV, Cooksey RC, Williams LB, Fawcett RL, Zhang P, Ambrosius WT, Whitfield RM, Jones R, Inman M, Huse J, McClain DA. Hexosamines regulate leptin production in human subcutaneous adipocytes. J Clin Endocrinol Metab. 2000 Oct;85(10):3551-6.
7: McClain DA, Alexander T, Cooksey RC, Considine RV.
Hexosamines stimulate leptin production in transgenic mice.
Endocrinology. 2000 Jun;141(6):1999-2002.
 
Thanks Bryan
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For the refeed days, which are mostly carbs, is a macronutrient breakdown of 25% protein, 65% carbs, 10% fat in the right ball park?

The diet Ive come up with based on what Ive read tonight gives these ratios for the refeed, but i can adjust if i need to (240g protein, 640g carbs, 40g fat).

If i did a two day refeed over the weekend, should the second refeed day have a lower total caloric intake? I dont know the answer to this, but id guess it makes sense?!? Ive gone for 4000 on saturday and 3000 on sunday (2200 during the week hypocaloric)

Please let me know if im heading for disaster anyone!
 
Those leptin refeeds are to apply only when u are dieting under manteinance right?
I ask this because I'm trying to bulk with quite low carb but around 300-500 Kcal over manteinance (a little "ondulating approach") and as I think to be slightly under 10% bodyfat I was wondering if I should have weekly refeeds.

Unfortunately I cant read those english papers easily but I am very interested about the topic because after this cycle (next month) I'm trying to have a cut cycle.
 
With a long refeed, your calorie surplus needs to be lower, and you have to be very careful with the junk.

If you do a very short refeed, you can go a little more nuts. . . a 48 refeed is very long, so while you should eat a surplus, you can't go over by as much. Also, with such a long refeed, you have to be very careful about fat intake during the refeed.

Rather than look at fat as a percentage of calories, look at it in grams per day. During your refeed, don't let you fat quantities go up significantly, compared to your regular baseline. The body's carbohydrate metabolism reacts very quickly to a change in diet, but the fat metabolism does not. It takes days to ramp up, so if you introduce a lot of extra fat in your refeed, a fair amount will be stored instead of metabolised. The longer your refeed, the more this is a concern.
 
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