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CARB CYCLING: ADVANTAGES ANDDISADVANTAGES 1 0 /0 4 /2 0 1 6

Similar to IIFYM, carb cycling is a hot topic in the fitness industrythese days. From followers of IIFYM to people who follow strictmeal plans, it seems that carb cycling as a nutritional strategy has

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spread its way into most sub-groups of dieters. It’s a pretty simpleconcept as the name says it all. Carb cycling involves changing yourmacro distributions around, mainly fat and carbs, for variousperiods of time. Technically, the definition of carb cycling could beextended quite wide as there are many forms. For example,someone could have a few high carb days a week followed by lowand moderate carbs for the rest of the week, while another personcould have high carbs for a full week followed by a week of lowcarbs. These are both considered forms of carb cycling. For thepurpose of this article, everything will be focused on the carbcycling strategy of 2-3 high carb days a week and the rest of thedays as low/moderate carbs.

What Exactly is Carb Cycling?

A typical carb cycling protocol involves switching up the macrodistribution with a mix of high/moderate/low carb daysincorporated throughout the week. Usually it will involve three highcarb days, two moderate carb days and two low carb days, butthat’s not a universal rule. The specific macro ratio of those daysjust depends on whatever the individual decides to follow. Carbcycling can be implemented into any form of dieting, from IIFYMand flexible dieting to rigid meal plans. The sources don’tnecessarily have to change as one would normally do with IIFYMthough, although they can. The only variables that have to changeare the amounts of each macro, primarily carbohydrates and fat.

There are a lot of proposed benefits to carb cycling. Some claim thatit leads to more calories burned or increased weight loss at the endof the week. Some say that extra carbs timed around exercise help

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performance so cycling carbs is good for said reason. Let’s take alook at what’s legitimate and what’s not.

The Benefits of Carb Cycling

In theory, it makes sense as to why carb cycling could be an effectivenutritional method. There are benefits that both increased carbsand increased fat can provide and carb cycling aims to takeadvantage of each macro. Timing carbohydrate intake aroundexercise is frequently recommended for the performance benefitsthat it provides.

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DAN B.

ALEXA S.

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Research has shown that roughly 1-2g CHO/kg taken 3-4 hoursbefore physical activity can improve performance, and it has alsoshown that ingesting a combination of protein and carbs beforeexercise can increase muscle protein synthesis (1). The effectscarbohydrates can have post-exercise are even better. Taking inample carbs right after a workout has been shown to stimulateglycogen re-synthesis at a greater rate and to further increasemuscle protein synthesis (1).

This essentially means that your body is fueling up for its nextworkout and utilizing protein more efficiently. If your diet wasconsistently low in carbs, it’s unlikely you would have enough ofthem to spread out between pre and post workout to reap the maxbenefits. It’s easy to see why ingesting a greater carbohydrateintake before and after exercise is a popular strategy to increaseperformance.

However, even though sufficient carbs timed around workouts canhave positive effects, what about the days that you’re not workingout and therefore not having the same amount of calories burned?If you’re not training on a given day, then why have the extra carbsfor performance benefits that will just be rendered futile? It seemslike it would make sense to have less carbs on the days that you’renot training and more carbs on the days that you are training. Ormaybe moderate carbs on your lighter workout days, and highercarbs timed around your more intense workouts.

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SEBASTIAN B.

MIRANDA E.

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The Effects of Differing Macro Ratios

One study took 40 individuals on the same number of calories anddivided them into a low carb and a low fat group with varying macroratios (2). The low carb group reported to have reducedglucose/insulin concentration and insulin sensitivity in comparisonto the lower fat group. The low carb group even experiencedgreater weight loss by a factor of 10%, indicating a greater numberof calories burned. Another study reported similar findings with thelow carb diet’s beneficial effects on body composition andinsulin/glucose levels (3). Diets higher in fat have also been linked togreater testosterone concentrations when compared to lower fatdiets(4). High test levels leaves more room for potential musclegrowth so this is obviously a good thing. Although the data onhigher fat intake is certainly positive, whether its benefits outweighthe pros of higher carbs is still up to debate.

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All of the research comparing various macro distributions isn’texactly consistent across the boards either. Another study assigned411 overweight individuals to four different diets with varyingmacro ratios and had them track their food for two years todetermine if there was a difference in calories burned or fat loss (5).Caloric intake was the same for all groups. It was found that thespecific macro ratios had no significant effect on weight loss orcalories burned, illustrating the point that overall caloric intake overmacro distribution is the most important factor when determiningweight balance and the amount of calories burned.

Although, it’s important to note that this study was conducted over

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a two year period, whereas the other two previously referencedstudies that gave favor to low carb diets were only performed over12 weeks and 16 weeks. A two year study utilizing a greater numberof people holds more merit in my book than studies done in a fewmonths with less people.

The Mental Advantage

These are just the potential physical benefits associated with eachmacro, but is there any type of mental advantage to carb cycling?Well, that’s going to depend on the person. Some people lovethe feeling of having a high carb day and get really excited

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whenever those days arrive. That excitement could help increaseadherence since it gives them something to look forward to multipletimes throughout the week. Not only for the aspect of being able toeat more delicious carbs that day, but also because the extra carbsshould help fuel that day’s workout and allow them to really pushthemselves.

Also, even though it’s not cheating on your diet, those high carbdays could make some people ‘feel’ as though they’re having abreak in their diet. In actuality they’re staying perfectly on track withtheir goals, so it’s a win-win scenario. This just depends on theindividual though. Some people may not see the benefit andtherefore it wouldn’t help them stay on track anymore than theusual approach would, but to others it could provide a nice mentaledge that assists with adherence.

The Effects of Leptin and Cortisol

Another important factor to consider with carb cycling is its effectson various hormones such as leptin and cortisol, both of which canplay a significant role in weight loss. Let’s take a look at leptin first.

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Leptin

What is leptin first of all? Leptin is a hormone that is responsible forcontrolling fat cell size and regulating hunger levels. The less fatyou have, the less leptin you have. The opposite also holds true.When leptin levels are above a certain threshold, they are releasedfrom fat cells which helps suppress your appetite and signals yourbody that it is full. At the beginning of a diet when people areholding more fat, leptin concentration is sufficient enough that thisusually isn’t an issue.

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Yet, as one loses more and more fat, leptin concentration is also

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decreasing which means your body has a harder time telling whenit’s full and therefore is always hungry. When your leptin levels fallbelow that certain threshold that tells your body everything is goodto go, your body essentially enters starvation mode and willconstantly remind you how hungry it is.

Clearly, this is not a good thing when calories are getting lower andyou’re already hungry as is. This is where a lot of people canstruggle to adhere to their diets since they’re hungry ALL the time.Itdoesn’t have to be all bad though. Even in a period of caloric deficitthere are some strategies that can be utilized to control leptin levelsto an extent.

Research has shown that meals high incarbohydrates can positively affect leptinconcentration in comparison to meals higherin fat(6).

One study tested 10 females in 3 day periods of carbohydrateoverfeeding and fat overfeeding. It was shown that plasma leptinconcentrations increased as much as 28% in the carbohydrateoverfeeding period when compared to the fat overfeeding(7).While this information is certainly relevant, it only covers thescenario of people having multiple high carb days in a row. Whatabout the carb cycling strategy of alternating daily betweenhigh/mid/low carb days?

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Another study was done that tested the effects of plasma leptinconcentration on 22 individuals after a single meal high in fat andagain after a meal high in carbs. The calories were the same for eachand measurements were recorded 9 hours afterwards. It turns outleptin levels were indeed higher in the high carb meal compared tothe high fat meal(8). This supports the notion that carbohydrateoverfeeding can have a positive effect on leptin concentrationregardless of whether it comes from a single meal, single day orperiod of multiple days.

Yet, it’s important to note that there isn’t an immediate spike inleptin levels after a high carb meal but the effects are more delayed.If you are truly trying to optimize all the benefits that increasedleptin can give you then I would recommend getting a lot of thecarbs earlier in the day as opposed to later.

Cortisol

Cortisol is a steroid hormone that is produced in the adrenal glands,

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it’s been nicknamed the ‘stress hormone’ since it is directly relatedto stress levels. High cortisol is equal to high stress. Chronicallyelevated cortisol levels have been linked to increased abdominal fatand decreased muscle mass… Clearly features we want to avoid.Cortisol is actually an important hormone that is required foroptimal health function, the issue is when it gets too high for toolong negative effects start coming in. Fortunately, there are someways in which we can help lower it that involves focusing on certainmacros.

There is mixed research on carbohydratefeeding being linked to cortisol levels. Somestudies have shown increased cortisol levelsafter a high carb meal where other studieshaven’t reported any noticeable correlationbetween the two(9).

The divided results don’t give a lot of support to carbs having muchto do with the hormone, nothing that can be 100% confirmed atleast. Research done on fat intake and cortisol is certainly morepromising and consistent across the boards though as multiplestudies have shown cortisol levels to significantly decrease whenmeasured after a meal high in fat (9). This definitely merits thebenefits of a high fat diet on cortisol levels over a high carb diet. Ifyou have a problem with consistently high cortisol levels, then a diethigher in fat could be a solid solution to help offset that.

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Breaking Down the Research

To sum it up in simple terms; high leptin levels are good and highcortisol levels are bad. In breaking down the research it seems thathigh carbs can increase leptin with no real effect on cortisol, andhigh fat can decrease cortisol with no real effect on leptin… Irony atis finest.

Of course the body just had to make things as complex as possiblesuch as it does with everything else. This essentially makes it a toss-up in choosing between high carbs and high fat in a weight lossphase, as it’s very hard to simultaneously increase leptin whiledecreasing cortisol when your body fat % is low and you only haveso little calories to work with. This is exactly where carb cyclingcomes into play since it aims to reap the benefits of both a high carband high fat diet. Based on the above research, it seems that carbcycling could be an excellent strategy to favorably control leptin andcortisol levels when calories are getting lower. ‘Seems’ is the keyword here. Until there’s a study conducted in this exact fashionwhich can confirm this, it just remains an educated hypothesis.

Is Carb Cycling Actually Effective or Not?

You may be more confused than ever now after the conflicting datathat I’ve presented you with. Despite there being some mixedresearch out there, the vast majority suggests that specific macroratios do not have an effect on weight loss or calories burned. At theend of the day, overall caloric intake will be the most significantfactor.

Unfortunately to my knowledge, there haven’t been any studies toWeb page converted to PDF with the PDFmyURL PDF creation API!

this date that have directly compared the effects of carb cyclingwhile keeping the same caloric intake throughout the week so this iswhat we mainly have to go by. Based on the research that isavailable though, I’m inclined to believe that the two methods wouldlead to the same amount of weight loss/gain over time assumingcaloric intake was the same at the end of the day or week.

For example, let’s take someone who eats 1,400 grams of carbs aweek. Assuming their overall caloric intake is the same at the end ofthe week, it technically doesn’t matter how they split up those carbswhen it comes to weight loss or calories burned. They could split itevenly into 200 grams per day, or they could have 300 grams onthree days, 150 grams on two days and 100 grams on the last twodays. From the standpoint of weight fluctuation and the number ofcalories burned, these macro distributions wouldn’t matter at all.

For this reason, to someone who strictly cares about weight losswith no focus on performance, then carb cycling may be largelyunnecessary and complicate a simple process that doesn’t need tobe complicated. There are a lot of other factors that can affectvariables such as performance and body composition, but weightloss is purely a matter of eating less calories than the number ofcalories burned.

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Despite the Research Presented

Even though macro ratios don’t have an effect on the number ofcalories burned or weight balance, I do think there are someindividuals who could still see benefits from carb cycling, though. Ifsomeone is only working out three times a week, carb cycling couldbe a great method to incorporate to really optimize those workouts.

For example, they could time three high carb days around the threeworkouts where they will need the extra carbs for performancebenefits, then consume low and moderate carbs on the other fourdays. The number of calories burned at the end of the week wouldbe the same, but there are some potential benefits that could beseen with timing a lot of their weekly carbohydrate intake aroundtheir workouts.

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A similar strategy of carb cycling could even be done with someonewho is working out 5 days a week. They could plan their high carbdays around their most intense workouts or around a lagging bodypart, moderate carb days around their less intense work outs, thenfinally low carbs on their two off days when extra carbs won’t beneeded as much. Theoretically, it makes sense that this could be aneffective strategy to optimize workouts with adequatecarbohydrate intake strategically timed while still having thepotential to see the benefits that a higher fat diet can provide. It’slike it’s the best of both worlds… In theory, that is. While it doesseem like it would make sense, as previously stated there areunfortunately no studies directly done on this that can confirm ityet.

In Conclusion

Ultimately, everything comes down to adherence. Whether or notcarb cycling will truly be effective depends on your personalpreferences and if you can actually stay consistent with it. Somepeople like to keep things simple and maintain a steady intakethroughout the week. Changing up the macro ratio in their IIFYMplan on a daily basis might be too stressful for some or too much ofa hassle to keep up with as it could be easy to mix up certain days upif they live a hectic lifestyle. For these people, I would recommend asteady carb intake throughout the week as that will more than likelyallow them to stay on track more. On the flip side, there are otherpeople who get bored eating the same foods and same amountsevery day.

If switching up the food sources weren’t enough for them already

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with IIFYM, then switching up the macro distributions multipletimes throughout the week might further help prevent things fromgetting stale. I know some people who really look forward toplanning out their high carb days, so being able to do that a fewtimes a week could be exciting and something to look forward to,increasing adherence. However, it is a double-edged sword at theend of the day because then that means there’s a couple days wherethey have to grind out on lower carbs. Maybe not an issue for some,but for other people it can be.

Why it’s worth considering it…

Another essential factor to consider with carb cycling is thatbecause the macro ratios are varying so greatly throughout theweek, the sources can as well. If someone was consistently low infat, then there would be a lot of foods that would be hard for themto fit in like peanut butter, red meats, etc. Likewise, if someone elsewas consistently low in carbs, then they would have a hard timefitting in foods like bread, pasta, etc. By switching up the macrodistribution on a day-to-day basis, you’re also allowing yourself thechance to eat foods you couldn’t normally eat as well. Obviously thishas no real effect on anything performance related, but it couldactually be a really big factor in making people adhere to their diet.

At the end of the day, the best diet is the one you can stick to.Whether you choose to cycle carbs vs. keeping a steady intakethroughout the week, the most important things are consistencyand adherence. Stay consistent in tracking your numbers withwhatever method you prefer, and the results will come with time.

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- REFERENCES

1. Kerksick, Chad, Travis Harvey, Jeff Stout, Bill Campbell,Colin Wilborn, Richard Kreider, Doug Kalman, TimZiegenfuss, Hector Lopez, Jamie Landis, John L. Ivy, and JoseAntonio. "International Society of Sports Nutrition PositionStand: Nutrient Timing." Journal of the International Societyof Sports Nutrition. BioMed Central, 3 Oct. 2008. Web.

2. Volek, JS, SD Phinney, CE Forsythe, EE Quann, RJ Wood,MJ Puglisi, WJ Kraemer, DM Bibus, ML Fernandez, and RDFeinman. "Carbohydrate Restriction Has a More FavorableImpact on the Metabolic Syndrome than a Low Fat Diet." USNational Library of Medicine. PubMed, 12 Dec. 2008. Web.

3. Gower, BA, and AM Goss. "A Lower-carbohydrate,Higher-fat Diet Reduces Abdominal and Intermuscular Fatand Increases Insulin Sensitivity in Adults at Risk of Type 2Diabetes." US National Library of Medicine. PubMed, 3 Dec.2014. Web.

4. Dorgan, JF, JT Tudd, C. Longcope, C. Brown, A. Schatzkin,BA Clevidence, WS Campbell, PP Nair, C. Franz, L. Kahle, andPR Taylor. "Effects of Dietary Fat and Fiber on Plasma andUrine Androgens and Estrogens in Men: A ControlledFeeding Study." The American Society for Clinical Nutrition.The American Journal of Clinical Nutrition, Dec. 1996. Web.

5. Sacks, FM, GA Bray, VJ Carey, SR Smith, DH Ryan, SDAnton, K. McManus, CM Champagne, LM Bishop, N.Laranjo, MS Leboff, JC Rood, L. De Jonge, FL Greenway, CMLoria, E. Obarzanek, and DA Williamson. "Comparison ofWeight-loss Diets with Different Compositions of Fat,Protein, and Carbohydrates." US National Library ofMedicine. PubMed, 26 Feb. 2009. Web.

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6. Izadi, Vajiheh, Sahar Saraf-Bank, and Leila Azadbakht."Dietery Intakes and Leptin Concentration." US NationalLibrary of Medicine. NCBI, 10 Sept. 2014. Web.

7. Dirlewanger, M., V. Di Vetta, E. Guenat, P. Battilana, G.Seematter, P. Schneiter, E. Jequier, and L. Tappy. "Effects ofShort-term Carbohydrate or Fat Overfeeding on EnergyExpenditure and Plasma Leptin Concentrations in HealthyFemale Subjects." US National Library of Medicine. PubMed,24 Nov. 2000. Web.

8. Romon, M., P. Lebel, C. Velly, N. Marecaux, JC Fruchart,and J. Dallongeville. "Leptin Response to Carbohydrate orFat Meal and Association with Subsequent Satiety andEnergy Intake." US National Library of Medicine. PubMed,27 Nov. 1997. Web.

9. Alleman, Rick J., Jr., and Richard Bloomer J. "HormonalResponse to Lipid and Carbohydrate Meals During theAcute Postprandial Period." Journal of the InternationalSociety of Sports Nutrition. BioMed Central, 11 Nov. 2011.Web.

A B O U T T H EA U T H O R

CORBINPIE RS ON

Corbin Pierson is anIFPA ProfessionalBodybuilder, aCertified Sports

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Nutritionist from theInternational Societyof Sports Nutrition(CISSN) and an ACEPersonal Trainer. Hegraduated from theUniversity of Kansaswith a BS in ExerciseScience. He works asa nutritionist andcontest prep coachthrough TeamPierson Fitness.Corbin has beencompeting in naturalbodybuildingcontests since 2010and has been afollower of IIFYM forabout 5 years, herecently won his procard while utilizingIIFYM and flexibledieting.

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Amayita • a month ago ⚑Impressive write up, thanks! I'm trying to stay as low carb aspossible, but I struggle. This info allows me to introduce a new highercarb day (within daily calories) and not feel guilty about it!

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