Lost 60lbs & Fixed insulin resistance with Atkins. Will juice fasting hurt my progress??

Juice fasts have no measurable benefits that you can't get from eating more vegetables. If you want to go low-fat for periods of time, then go low-fat for periods of time and replace the fat with whole fruits and nutrient-rich starchy vegetables like sweet potatoes. If you want to fast, then fast. Look up Intermittent Fasting, it definitely has benefits to insulin sensitivity and doesn't have all of the "woo" of juice fasts.

Would it be detrimental? Self-directed, radical dietary changes in any direction are rarely a good idea. The thing about juice is that you lose much of the fruit or vegetablefiber bulk that would otherwise slow sugar digestion and absorption as well as providing the other benefits associated with fiber. Please get that advice from your physician (as you intend to) as (1)nobody on the internet is qualified to give you medical advice and (2)the internet is a magnet for people who wish to be "helpful" despite no foundation in medicine or nutrition. A referral to a registered dietician could set you up with someone qualified to work with you longer-term to arrive at an enjoyable diet that provides you with the nutrition you require.

Eating high fat and low carb in the long term will noy hurt you. Read Good Calories, Bad Calories or Why We Get Fat (both by Gary Taubes) if you need convincing of this. No AskMeFi answer will be a fraction as informative or persuasive as either of those books, nor as well-cited.

First question: What is your goal with juice fasting? You don't really state what you're looking for, and there's no benefits that I know of. And yes, the high sugar contents of the fruits will mess up your insulin just as if you decided to start eating bread/rice/potatoes. And going low/zero fat is not a good idea - fat is good for you! You can stay low-carb for essentially forever w/o issues. If you want to take this to the next level and go super-low-bodyfat, check out "carb cycling", it's what bodybuilders do to burn off that last bit of bodyfat. BUT going So..to restate, what is your actual goal? What are you looking for with juice fasting that you're not achieving now? You really need to focus on healthy goals, and *then* figure out how to get there. Don't be looking at random diets and asking what they'll do for you. BTW, most every "cleansing" and "detox" diet is bunk - they only provide temporary changes, are usually detrimental, and the rebound leaves you worse than you started. As you've learned already, real changes come from slow, long-term lifestyle improvements. There is no shortcut to health.5>

Just think about what is even vaguely 'natural' for humans: - eating tons of refined carbs (no - as you found out) - eating more protein and fewer carbs (yes - as you found out) - starting to add in more vegetables, reduce the fat, keep protein high, and add in a few carefully chosen carbs (yes - that's what many people do post-atkins, and it lets them maintain their weight loss AND be interesting enough to be sustainable in the long-run) - juicing fruits & vegetables instead of learning how to incorporate them into your overall diet and meals (not really a great approach to life-long nutritional habits)

You've found something (low carb) that's worked really well for you. Why suddenly switch to another thing (juicing) that is pretty much the exact opposite? If you need more carbs for exercise - which it really sounds like you do - try adding more healthy carbs slowly. You can add fruits and vegetables (whole, not juiced), legumes, whole grains. It will probably work better to make this change gradually rather than suddenly dumping a lot of sugar into your system.

I would suggest looking into South Beach, since it addresses the downsides of Atkins which you seem to be looking to bypass (although to be fair, I never did much research into Atkins and most of what I know is from other people who have done it). South Beach has a similar premise, but specifically guides you towards eating a very healthy diet which is not super high in fats, and contains lots of vegetables.

You mentioned that you added additional avocados, nuts, and yogurt to the mix with no ill effects and no weight gain, what about just doing the same with vegetable juices? Add a kale/carrot/beet/whatever juice in the morning, eat how you normally do the rest of the day, and then see how you are feeling/weighing after a few days of this. Then, add something else - more juice, a piece of fruit, etc. and see how you feel and how your body responds. Maybe making one modification every week and giving it a week or so before modifying something else. On preview - what platinum is saying as I too am familiar with the Atkins diet and finding your ACE. I don't think it is smart to go from one "extreme" diet to another (not that I personally think atkins or a temporary juice fast is extreme but they are pretty different from one another).

You say you're doing a "modified Atkins." Are you using the http://www.amazon.com/exec/obidos/ASIN/1439190275/metafilter-20/ref=nosim/? Have you moved through all four phases? Have you found your ACE? The book actually lays out exactly what steps you should take to slowly and safely add more nutrients and carbs back into your diet until you reach your carb equilibrium and how to maintain it over the long haul. If you are reading an older version of the book or are more or less making it up as you go along, I highly recommend that you pick up the new book and give it a read through. I think you'll find exactly what you're looking for already laid out there.