The low-FODMAP vegan diet essentially has three phases:
The elimination phase generally lasts for two to eight weeks and the objective is twofold:
A 2014 study conducted at Monash University showed that the most significant symptom changes occurred within the first seven days of being on the low-FODMAP diet. This means that if the diet is going to be of benefit to you, it will likely be apparent fairly quickly. Broadly speaking, people with faster gut motility (such as those with IBS-D) will typically see results sooner than those with slower transit times (such as those with IBS-C). That's because the problematic carbohydrates (FODMAPs) must be in the intestine to cause symptoms, so the faster they exit, the faster symptoms are relieved.
During the elimination phase, the objective is to remove all high-FODMAP foods from the diet. This provides a real test of whether the diet is going to work for you. If your symptoms are improved during this phase, you can start a systematic reintroduction of some higher-FODMAP foods in small amounts to challenge your tolerance of them.
This reintroduction phase is a period of discovery. During this phase you may find that particular foods are more tolerable at certain times of your life, such as when things are less hectic and stressful. For that reason, occasions when you have more privacy and are under less pressure (such as during the weekend rather than the work week) might be a better time to attempt a food challenge. For obvious reasons, avoid reintroducing potentially problematic foods during high-stress periods, such as holidays, family gatherings, business meetings, important functions or events, or when you're traveling. Keeping a food journal or diary during this phase may be helpful. Be sure to include not only all the foods you consume (including snacks) but also the amount of each food and how you felt after eating it.
One of the stranger hallmarks of IBS is how symptoms can vary throughout our lives, and food triggers may fluctuate as well. Consequently, what instigates your symptoms one week or month may end up being more tolerable the next. So continue to challenge yourself over time, even with very small quantities of high-FODMAP foods, to ensure as much variety in your diet as possible.
The ultimate aim of the low-FODMAP approach is to have as liberal a diet as you can tolerate. That's the maintenance phase. However, there may be occasional periods when your symptoms flare and you need to return to a more restricted low-FODMAP regime for a while, and that's perfectly okay. It doesn't mean you did anything wrong, or that the diet failed you, or that your body let you down. Because IBS is so unpredictable and is affected by many potential triggers other than food (including stress, emotional upset, poor sleep habits, lack of exercise, other illnesses, and the normal challenges of life), flare-ups are bound to occur. When they do, the low-FODMAP diet can provide some welcome relief and pampering for your delicate digestive tract while you pamper the rest of your body, mind, and spirit.