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Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...

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November 15, 2017

Does Carb Cycling Work? It Depends.

By Mark Sisson
53 Comments

The word "CARBS" written in vintage ink stained letterpress type.Keto may not be for everyone, and low-carb is not the only way to eat well, but most would agree that people in the modern world tend to eat way too many carbohydrates—far more than their lifestyles and activity levels warrant. Along with some other big factors, excessive intake of refined carbohydrates is a major player in the modern epidemics of obesity, diabetes, heart disease, and other disorders. This is no longer controversial. Reducing carbs is a good move for most folks.

The majority of my readers are on some kind of low carb diet. Maybe they’re not fully keto. But they all tend to acknowledge the utility of limiting one’s carbs to only those they need. One of the more common questions I receive from this group concerns carb cycling—periodically adding more carbs to an otherwise low-carb diet.

Should it be done? If so, do certain contexts make carb cycling work better or worse?

Let’s have a discussion.

The main reason people here want to introduce additional carbs to their regularly scheduled keto or low carb diets is for the supposed performance benefits. Fat and ketones are great for slower, less intense movements like hiking, jogging, and other endurance activities, the story goes, but you really need glycogen to power intense, anaerobically-demanding pursuits like CrossFit and sprints and powerlifting. Since carbs are the easiest way to replenish muscle glycogen, low-carbers who care about their physical performance need to eat carbs. That’s the conventional wisdom, at least.

Enter the cyclical ketogenic diet, a regimen that promises to let you have your cake (of varying macronutrient ratios depending on whether it’s refeed day) and eat it too. Reap the benefits of keto—improved fat-burning capacity, increased endurance, boundless energy, caloric efficiency, clear-headed cognition—and of carbohydrates—increased power output, fully-stocked glycogen reserves—with none of the downsides.

Does it work?

Formal research is quite limited at the moment. What we have suggests that certain forms of cyclical ketogenic dieting are unnecessary at best and counterproductive at worst.

One recent study actually tested this, pitting ketogenic dieters against cyclical ketogenic dieters for fat loss and exercise performance. The keto dieters stuck to a typical keto diet for the 8 weeks—75% fat, 20% protein, 5% carbs. The cyclical keto dieters were keto 5 days a week and spent 2 days refeeding on carbs. Throughout the study, both groups lifted weights 3 times a week and did high intensity interval training (HIIT) twice a week. When the 8 weeks were up, they ran some body composition and performance tests.

What happened?

There were no differences in performance. All those carbs—16 days of carb refeeds—weren’t enough to help the cyclical keto dieters perform any better in the gym than the keto dieters. And this was strength training and HIIT, which are supposed to require carbs for optimal performance.

There were differences in body composition. The keto group lost more body fat and didn’t lose any lean mass. The cyclical keto group lost less body fat and significant amounts of lean mass. You can’t get any more stark than that: Keto was way better for body composition.

My takeaways?

I see a lot wrong with the 2-day refeed approach. For one, these subjects were trying to adapt to keto. They weren’t experienced. Right off the bat, that’s a lot of time to be gorging on carbs while ostensibly trying to become keto-adapted. Hard to make good adaptations when you’re doing 2 days of high carb every week. One step forward, two steps back. 

I imagine “targeted keto”—eating small boluses of carbs before/after training—would work better than 2 day refeeds. Hopefully, research into that type of carb cycling is coming.

These guys were training pretty hard, and pretty Primally: 3x a week lifting, 2x a week HIIT. It seems like basic strength training isn’t glycogen-dependent enough to warrant 2 day carb feeds. Seems HIIT isn’t either, though I didn’t catch the exact protocol.

They also did a followup with the same groups where they reintroduced carbs in two ways. One group slowly introduced carbs, little by little, eating 1 grams per kilogram of bodyweight per day. The other group just went whole hog, eating 3 grams of carbs per kilogram of bodyweight each day. The former group gained little to no fat, and was even able to put on lean mass. The whole hog group gained more fat and failed to gain lean mass. To me, this supports the notion of small targeted doses of carbs when refeeding, rather than massive binges.

Other studies find that for strength training—basic moderate volume lifting—keto is great. You need some initial glycogen to help with the lifts, but you don’t need to constantly refill it. Besides, and many people forget this, you still have glycogen on keto. You still refill it on keto, just more slowly. Doing something like CrossFit four days a week probably works better with some carbs because it’s so glycogen-dependent and you’ll need quicker repletion. Yet, even CrossFit WODs are doable on keto, provided you give your body enough time in between sessions to recover.

What about gains? Don’t we need carbs to build muscle? Studies show that the insulinogenic effect of protein alone is adequate for post-workout muscle protein synthesis. Adding carbs doesn’t augment the effect. And research on full-blown ketogenic trainees shows they can effectively gain muscle.

Another reason people wonder about carb-cycling is to overcome fat loss plateaus. There’s some truth to this, as I discussed several years ago in a post on carb refeeds and weight loss.

Spending too long a time in a low-carb, calorie-reduced state can reduce leptin, a hormone that regulates energy expenditure. Low leptin, low energy expenditure, higher appetite, harder weight loss.

A short carb refeed can boost flagging leptin levels enough to spur additional fat loss.

But as the previous study shows, carb refeeds won’t improve your body composition (they’ll actually worsen it) unless you’re already fat-adapted. I’d go one further and say carb refeeds won’t help you lose fat unless you’re fairly lean. They’re better for the person battling those last few stubborn pounds than they are for the obese person just beginning their weight loss journey.

If you still want to carb cycle, heed these suggestions:

  1. Make sure you need the carbs. You should be doing serious glycolytic work that depletes muscle glycogen on a regular and frequent basis. Think CrossFit. Think jiu-jitsu. Think hill sprints for 30 minutes. Lifting and doing sprints might not be enough to require extra carbs.
  2. Do targeted refeeds, rather than free-for-all benders. Consider 20-30 grams of carbs with your workout, not 2 days of bear claws and pizzas. Besides, you can always add more if the initial dose wasn’t enough.
  3. Get adapted first. Don’t get ahead of yourself and shortchange your results. The most scientifically-validated complex carb refeeding scheme won’t do anything if you’ve only been keto for three days. Wait six weeks (at least) to adapt, and then try.
  4. Don’t refeed because you miss French fries. Refeed because you have actual reasons.
  5. Don’t refeed because you’re going through the keto flu and want to alleviate the discomfort. Read my post on the keto flu and push through.
  6. If you’re refeeding to lose body fat, make sure you’re truly on a plateau. “Being on a plateau” assumes you’ve lost significant amounts of weight and are now stuck. It doesn’t refer to those just getting started.

Few people truly need to carb cycle. It can be helpful for certain situations, provided you satisfy the criteria outlined above, but don’t think it’s a requirement for healthy dieting.

It’s nice to have options, though. Hopefully after today’s post you know what your options actually are.

Thanks for reading, everyone. Take care, and be sure to leave your thoughts and reactions down below.

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53 Comments on "Does Carb Cycling Work? It Depends."

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Katie
5 months 10 days ago
I had to do a little self-reflecting yesterday regarding my fear of simple carbs. I’ve been free of sugar for quite a while, and as I sat down in the dentist chair for a crown repair the hygienist asked if I’d eaten breakfast. I told her about my fatty coffee and she frowned and said that wouldn’t work as the numbing solution needed glucose to work. She made me drink a box of apple juice! I was horrified when I looked at the ingredient label: 24 grams of carbs and sugar! It was pure sugar! And I didn’t even want… Read more »
Elizabeth
5 months 10 days ago

Katie, I agree with you. I’ve been primal for so long but having some sugar from time to time doesn’t seem to throw me off too much anymore.

Layla Masant
5 months 9 days ago

Hmm… I’ve been happily in ketosis for 10 years and redently got novacaine from dentist to cap a chipped tooth. No glucose-loading required!

TeeDee
TeeDee
5 months 9 days ago

Same here, Layla and I’ve never been asked by my dental hygienist or dentist if I’ve eaten, nor have I ever heard of needing glucose for the novocaine to take effect!

Shary
Shary
5 months 10 days ago
I do mostly 90/10 Paleo and don’t bother with keto. For me, a “refeed” is occasionally dropping back to 80/20 Paleo and treating myself to a modest increase in (mostly) healthy carbs, such as potatoes and other root veggies, rice, legumes, etc. I’m at a normal weight, but when I was trying to lose a few pounds I found it worked much better to be fairly strict with myself. A two-day refeed every week would have gotten me nowhere. There’s also a mental factor to consider. It’s way too easy to go from two days of “carbing out” to falling… Read more »
Katie
5 months 10 days ago

I agree, Shary. For me, a two day refeed every week might make it harder for me to get back on track.

Marissa
Marissa
5 months 10 days ago

Just my n=1, I thrive well cycling carbs with keto 20-30 g Monday to Friday and weekend refeeds. The benefits I’ve noticed include 1) improved endurance and lifting performance 2) helps regulate hormones – I retain water when eating low carb consistently with my activity level and invariably the refeeds help me drop that water which I assume to be a cortisol effect. I will add that I think some of the benefits are a calorie effect as I struggle to eat enough on weekdays. I also think there is value in not being in ketosis all the time.

Daniel James Taylor-Shaut
Daniel James Taylor-Shaut
5 months 10 days ago

I find that eating some oatmeal in the morning suits me well. If i only eat fats, protein, and tubers (in addition to veggies), I find that I often require more calories or am hungry. I don’t see the need to forcibly starve myself. Yes, sure, intermittently I may eat less if traveling or on the road, but otherwise why do it? I fast when I sleep and don’t have any noticeable health issues. Furthermore, whenever I go keto or low carb I ALWAYS feel tired and have hormone issue, feeling under-recovered. That just doesn’t seem appealing.

Shruti
Shruti
5 months 10 days ago

Yep, this is me too. Primal + oatmeal 3x a week or so. Way to know yourself 🙂

Lynne ryan
Lynne ryan
5 months 10 days ago

Great article. I’ve been wondering about cycling but more for the hormonal health for us women in our 50s. I’ve seen quite a few hard exercising females mess up their adrenals with keto style diets. Any info would be appreciated.

Carla
Carla
5 months 10 days ago

I am curious as well

Hawke
5 months 10 days ago
I agree as well. I am menopausal being doing keto 8+ weeks and no real fat loss but still other benefits, no hunger, mental clarity, less inflammation. I am a Spartan athlete /run and of course workouts still suck as not fat adapted. But lack of fat loss puzzled me at 50-60 gms a day 30 or more of these are fiber. Well I got my head chopped off at another Keto site saying my carbs still too high and I need to lower to lose weight. Because of insulin effect. Well my blood sugars are super, my insulin last… Read more »
Layla Masant
5 months 9 days ago
Hi ladies, I’ve been in ketosis for over 10 years and I’m now 62. Was personal trainer and yoga instructor for years in my 40’s. Never over-trained and have never regretted it. Now in ketosis I don’t over-do my fitness because it’s not necessary! I hardly have to show up at the gym to stay fit. I believe my blood type 0+ lets me thrive with very few carbs, yet in the winter months I will eat some root vegetables and use coconut flour, with no problems. Fat-burning state is the best thing that ever happened to me. I sometimes… Read more »
Layla Masant
5 months 9 days ago
My point is that if your body is happy in ketosis, it will tell you if/when to eat a few more carbs and even what type. It will also tell you how much exercise is just enough to feel in good shape. No need to measure and analyze stuff, unless you enjoy that! The markers I use are good sleep, stable mood, solid muscle mass, glowing skin, stable energy and stamina, and ability to move fast and lift heavy only when you NEED to (like scoop up your grandkids when they want a hug, run to catch a train, dance… Read more »
Timothy
5 months 10 days ago
Great topic and one crying out for much additional experimentation. My contribution: once fat-adapted, cycling carbs never fails to achieve very low levels of body fat (~5-6%). I’ve done this annually since 2010, having gone through a few months of very low carb in 2009 when I first discovered MDA. I’m now 41. You can see the visible results of this year’s diet at urbanprimalistcom.wordpress.com (About section) and judge for yourself whether cycled carbs work. Earlier results can be found by clicking on my name on this post. To be clear, my goal with this protocol is extreme reduction in… Read more »
TeeDee
TeeDee
5 months 9 days ago

What makes things confusing is to read about your particular experience with carbs, only to then read about those who have been doing Zero Carb for years. The zero carbers I’ve met on Twitter for example are weight lifters, runners and competitors from all walks of life. Personally, I’m keto and not zero carb, but it’s intriguing. If you’re on Twitter, check out Sean Baker (MD) and see his record-breaking stats and physique while taking in no carbs at all..

Timothy
5 months 9 days ago
Agreed, there are a number of extraordinarily fit chronic keto dieters. Thanks for the referral to Sean Baker. Luis Villasenor is another great example and has been very-low-carb for several years with no shortage of strength. Certainly his thyroid is not “broken” contrary to one counter-argument. Whether cycled carb or permanent very-low-carb is superior can only be settled by n=1 experimentation. For now, I embrace ketosis in winter and cycled carb in summer because 1) Cycled carb has worked every time I’ve tried it to drop fat while keeping strength, and 2) All human ancestors outside of the arctic circle… Read more »
TeeDee
TeeDee
5 months 8 days ago

You’re absolutely correct that n=1 experimentation is the key to getting things right for our own particular situation. I’m concerned when I see someone who needs to lose significant weight, has low to moderate activity level or perhaps needs to reverse T2 Diabetes consuming ‘fat bombs’, carb cycling, etc. when it may not be appropriate for their health needs. The plan you’ve developed for yourself sounds more than reasonable and is obviously giving you the results you want..

Timothy
5 months 8 days ago

Very good point that somebody at the start of their journey has very different problems to solve than those who are already athletic and trying to fine-tune performance.

Our very first priorities should be 1) avoiding toxins and 2) repairing nutrient deficiencies that have been worsening over years, if not decades. That was me several years ago. This means eating plenty of real paleo food and worrying about macro manipulation later.

What breaks my heart is seeing people newly introduced to paleo filling up on powders, pills, and machine-assisted indoor exercises. This misses the entire point and gives “paleo” a bad rap…

Mike Trinchitella
5 months 10 days ago
Interesting discussion Mark I’m glad you posted this. I’ve been following a cyclical ketogenic diet since the early 1990s even before Lyle McDonald wrote his book in fact I was doing it before and while he was doing his book and we were all members of the low carb list-serv way back in the day. Then we both played around with BodyOpus via Dan Duchaine. So I’m definitely a vet in regards to a ketogenic diet. That being said I was one of the speakers last year in Las Vegas along with Ryan and Jacob Wilson who did that little… Read more »
Jea
Jea
5 months 10 days ago

Did this study only include loss/gains? Long term keto diets can break your thyroid. I found refueling every 5 days with a cup of starch/carb gave me more energy and stamina. Not two days of carbs.

Timothy
5 months 10 days ago

I did not know that about long term keto diets. Would you explain what “break” means in this context and point me towards a citation? Thanks!

wildgrok
wildgrok
5 months 10 days ago

I do my carb refeeds with IPA beers

Patrick
5 months 10 days ago
I have to agree Wildgrok. All primitive societies ate carbs whether it was tubers or a small amount of grains. They all consumed this with a LOT of fat to basically soak up the fat. Chicken fat on its own is not very tasty but when it is poured over a potato it becomes gorgeous. Groks all over the world ate SOME carbs but nowhere near what is now the norm and ALWAYS ate them with plenty of natural fat. I think this whole topic is becoming a bit nerdy. Find out what works for you and what feels right… Read more »
wildgrok
wildgrok
5 months 9 days ago

Agreed: the IPAs feel very right in my body 🙂

BeesMakeHoney
BeesMakeHoney
5 months 9 days ago

I do mine with Porters and Stouts. Of course I don’t call it a refeed.Every”body” is different, and our taste BUDS reflect that 🙂

Jeff
Jeff
5 months 9 days ago

I’m with you on that wildgrok, I find myself doing quite a few IPA carb refeeds! How’s it working for you?

wildgrok
wildgrok
5 months 9 days ago

It works wonders: if you choose the right IPA you only need one to get the nirvana-bliss-refeed effect, I recently discovered one with 10 degrees of bliss effect (*). But the ones with 8 and 8.4 work very well (grab a 7 if none available at the time in the supermarket)

(*) alcohol content 🙂

John
John
5 months 9 days ago

I’ll second that!

Claudius
Claudius
5 months 10 days ago

What’s your opinion Mark about this”new” Visual Impact High Carb Fat Loss diet from Rusty Moore and Mark Kislich?…it appears very controversial!

Diva Osorio
Diva Osorio
5 months 10 days ago

I have followed a one day carb refeed protocol for the last 8 years and 9 weeks ago I decided to drop my carb refeed day and just do a TKD approach, with 20-30g carbs pre workout and sometimes tubers post workout, if my next session is only a few hours apart to the first one. I’m a CrossFit athlete. Im loving the new TKD approach and honestly, I don’t miss my carb refeed day at all!!

Mathieu
Mathieu
5 months 10 days ago

Would have been interesting to have a third group with daily (good/smart) carbs (so not low carb per se).
I think I know which group would have had the best performance for intense workouts… 😉

NaturalGirl
NaturalGirl
5 months 10 days ago

I tend to listen to my body, “as needed.” I stay quite active and like to pick and choose carbs depending on my day…

Michael
Michael
5 months 10 days ago

I’ve been eating paleo for the past 2 years. Just recently I’ve reintroduced 300gms of white rice into my diet daily, mixed into steamed vegetables, salads etc. I’ve found my energy levels a lot better considering I do a fairly physical job. It’s really helped. Do you see a problem with doing this?

BeesMakeHoney
BeesMakeHoney
5 months 9 days ago

FWIW
If it is working for you – I see no problem with it. We all have different goals/lifestyles/bodies/brains. I personally think N=1 is the only reliable way to gauge a result when I make a change.

Elizabeth
5 months 10 days ago
Interesting post. I talked to someone recently who carb cycled and seemed pretty miserable. It sounded like a lot of work to track everything. I’ve been fat adapted for years now and feel great, but there are still days when I eat more carbs. Never processed carbs…just not worth it. But totally cool with some sweet potatoes or even a small portion the lentil pasta every now and then. Or some really good chocolate. I always do it later in the day. Should also mention that I definitely notice more of a craving for carbs when I’m sleep deprived (which… Read more »
2Rae
2Rae
5 months 10 days ago

A dog bartender, cool……

well, that’s how I first read it.

Jeff
Jeff
5 months 10 days ago

This post reinforces my belief that the only times to eat carbs are before, during, or after exercise.

HealthyHombre
HealthyHombre
5 months 10 days ago
Fascinating stuff and read everyone’s posts, really thought provoking and some experts supplementing Mark’s great offering as well as past success story folks with a great perspective. I’ve posted similar thoughts in the recent past, but again … here we go … when you read about the long-lived Blue Zone people they have a natural, unforced lifestyle that involves lots of movement, fresh air and sunshine, good sleep, a relatively stress free life with gratitude and purpose, lifting things when needed, gardening (often growing their own vegetables and herbs and fermenting food), lots of social and family activity, and primarily… Read more »
Tara
5 months 9 days ago

I am a big advocate of the ketogenic diet as a mainstay, but I think that cycling in and out is optimal. We have two (well, really 4) energy sources. I think it benefits us to optimize them both. If we eat more seasonally, with low carbs in mind, I think the question answers itself.

reamika
5 months 9 days ago

Glad you talked about this Mark, I would be interested on what results would be for fully fat adapted people doing targeted carb cycling. That’s pretty much what I do, and I have to say, it’s mainly because of the pleasure some carby foods give me. Especially now in autumn, with all the kabocha and delicata squash, sweet potatoes etc. I just try to eat these on workout days, and to be honest my goals are simply optimal health rather than fat loss or workout performance! Maybe a post on how all this factors into longevity goals next time? 🙂

T Money
T Money
5 months 9 days ago

Great information here and perfect timing for me. Couldn’t agree with you more Mark and getting the glycolitics (if that’s a word) down is key as I try to stay fit and practice Jiujitsu as much as possible and find that I need to increase clean carb intake just slightly to stay strong and capable. You just have to listen to your body. It will tell you almost everything you need to know.

Lisa L MacKenzie
Lisa L MacKenzie
5 months 8 days ago

Hi I’m very very new to this way of eating, this blog is the first I’ve EVER read. Fruit and veg are carbs right? So if I cut them out (to cut the carbs out) where do I get all those nutrients from? We all know that poor quality supplements (and there are so many of them out there) are worthless to our health. Please help.

HypoHarriet
HypoHarriet
5 months 7 days ago

Not all carbs are created equal. Usually when people refer to low-carb diets, they’re talking about removing processed, simple carbs, like sugars, pasta, bread, cake, etc. from your diet. Veggies are fine! In fact, vegetables should be a significant part of your diet. Fruits are debatable, though varieties with lower sugar are best. Go for berries or grapefruit and stay away from high sugar fruits like ripened bananas. Depending on your needs, you might also want to avoid high-carb tubers, like potatoes. Go for whole foods and avoid all the processed garbage.

carlos
carlos
5 months 8 days ago

Theres a docu series on-line IThrive, about diabetes that really dishes out ketogenic diets.
any comments?

Jimmy Smith
5 months 8 days ago

Good article and I particularly liked the little bullet point at the end about “getting adapted first”. I think the long view of nutrition in terms of “where will I be in eight weeks” is so much more effective than “what diet should I use today”.

nate b.
nate b.
5 months 8 days ago
I was a big advocate of low carb / high protein diets for the last 6 years. Unfortunately, it is not for everyone nor everyone’s body. I went into ketosis and ended up with high levels of ammonia in my blood. I was in and out of the E.R and had no idea what was going on. We have to remember that hunter / gatherer tribes did not eat a steady diet. Quite the opposite. The theory of a lean sinewy meat eating man is quaint but fictional. High levels of any macro-nutrient be it Carbs, Fats, or Protein garner… Read more »
Claudia
Claudia
5 months 7 days ago

I think I don’t need that binge on carbs. Although It has been hard to lose fat (people say it is because I am above the 50 th), I don’t believe it. I’d rather research more about keto diet beccause I am sure I have not been following the protocol accordingly. If someone at 50 ths or more can help, I would love. Does female hormone block my weight loss? I am seeing a doctor next Monday.

Hadassah-Rivkah
Hadassah-Rivkah
5 months 3 days ago

I am new to Keto but have heard from a couple people I follow that cycling some carbs is good for a womans hormones. I would also like to know if you have an article on Keto and low moods as I have heard that can be a side effect. I want to avoid having such a side effect. Thanks! Appreciate the well written articles here, just poking around for the first time.

Chloë
Chloë
4 months 29 days ago
I commute to university 3 days a week, which is roughly ten miles (round trip) very hilly with some really steep climbs. I eat very low-carb, (never grains, refined sugar, white potato etc, I even eat very limited amounts of fruit & root vegetables) and I remain in ketosis most of the time. I eat in narrow eating windows, usually between 11am – 3pm because I am in University 9am – 7pm and thats the only window I get (I don’t feel there is time for breakfast and I hate to eat after 7pm because digestion inhibits my sleep) The… Read more »
Tom
Tom
3 months 30 days ago
How about carb cycling if you get high blood glucose whilst doing keto? Mark mentions (in 21 day reset book) this happened to him and co-author – and it’s really important: e.g. For those doing keto for cancer management a high glucose level is totally counter-productive (Mark theorises it can happen when body gets to prefer ketones over ingested glucose and starts to ignore insulin’s efforts to provide it, leaving glucose to pile up in the blood). If so, what solution? A few weeks keto, then a week low carb but not to keto extent? (To maintain insulin sensitivity). Would… Read more »
Tom
Tom
3 months 28 days ago
How about carb cycling / cyclical keto when you get insulin resistance due to being in ketosis?! Mark mentions in 21 Day Reset that he and co-author both got ‘pre-diabetic’ blood glucose results at times and theorises this could be due to being so ketone adapted that cells start ignoring insulin leading to accumulation of glucose in blood: a nightmare if doing keto to manage cancer and deprive cancer cells of glucose. I have recently come across the same high glucose readings (around 100) while keto. How to avoid this? 3 weeks on keto, a week or so off (but… Read more »
Nelly
14 days 12 hours ago

Such a great article! I love visiting a spinning class, but when the weather is nice there is nothing better than riding a bike on your way to work.

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