What (and When) to Eat Before a Workout — If You Have IBS or Pre-Diabetes
Written by Anne-Marie Sawula, Registered Dietitian, RD CDE - Registered Dietitian specializing in pre-diabetes & gut health.
There’s so much conflicting information online about what to eat before a workout — especially if you’ve been diagnosed with IBS or pre-diabetes.
Should you train fasted? Should you eat carbs? How much is too much? It can feel overwhelming!
Like everything in nutrition: it depends.
What you eat before you exercise depends on:
The type and intensity of your workout
Your last meal
How sensitive your gut is
Your blood sugar response
And of course, your personal goals
But one thing is clear:
Fueling well before a workout helps you feel better, perform better, and recover better — no matter your diagnosis.
Why Pre-Workout Nutrition Matters
When you fuel with intention, you can:
Support steady blood sugar during and after exercise
Avoid unwanted gut symptoms like bloating or urgency
Have enough energy to train
Support muscle repair and recovery
Let’s break it down with flexible options for different timing — and digestive/blood sugar needs.
2–4 Hours Before Your Workout
This is your best window for a balanced meal that helps stabilize blood sugar and reduce GI symptoms.
If you struggle with bloating or urgency, go easy on raw veggies, legumes, and high-fat foods.
What to aim for:
Lean protein
Low-GI carbs (whole grains, starchy veg (potatoes, sweet potatoes), fruit)
A little healthy fat
Cooked, easier-to-digest vegetables
Example Meal Ideas (2–4 hours pre-workout):
Scrambled eggs on sourdough toast with cooked spinach and a banana
Grilled chicken with roasted sweet potato and zucchini
Quinoa bowl with tofu, roasted veggies, olive oil, and a small portion of avocado
Brown rice pasta with ground turkey, bell peppers and zucchini in a tomato sauce (low-FODMAP if needed)
60–90 Minutes Before Your Workout
This is a great window for a smaller meal or substantial snack. The goal here is to top up energy while keeping digestion smooth.
What to aim for:
✅ Easily digestible carbs
✅ A moderate amount of protein
🚫 Keep fat and fibre low to avoid gut upset
💧 Hydrate — sip water or a low-sugar electrolyte drink
Carb goal: ~0.5–1 g/kg of body weight
Protein goal: ~15–25g
Example Snack Ideas (60–90 mins pre-workout):
Smoothie with lactose-free milk, banana, oats, and protein powder
¾ cup Greek yogurt + cooked berries + drizzle of maple syrup
1 slice toast + 1 hard-boiled egg + kiwi
Low-fibre cereal with milk (e.g. Cornflakes or Rice Krispies)
If you’re managing pre-diabetes, pairing carbs with a little protein or fat helps keep your blood sugar more stable.
30–60 Minutes Before Your Workout
Short on time? Focus on quick carbs and hydration — and keep it super gentle on your gut.
Skip heavy protein, fat, or fibre here — these can slow digestion and lead to cramping or urgency.
Some individuals with a sensitive gut find it helpful to choose low FODMAP options closer to their work-out window.
Snack Ideas (30–60 mins pre-workout):
Yellow-green banana (low fodmap
½ cup fruit purée or unsweetened applesauce
A handful of rice crackers + a few sips of electrolyte drink
1 medjool date or ¼ cup dried cranberries
½ cup juice or 1 cup lactose-free milk
What About Caffeine?
Caffeine can improve performance, especially for endurance or high-intensity training. But for those with IBS, caffeine may worsen urgency, cramping, or reflux.
If you're sensitive, skip it or opt for a smaller dose (e.g. ½ cup coffee or green tea).
💡 Target: ~3 mg/kg, ~60 mins before exercise, if tolerated.
Hydration Matters, Too
Start sipping fluids a few hours before training. You don’t need to chug, but aim to:
Drink ~250–500 mL in the hour before
Choose water, lactose-free milk, or a low-FODMAP electrolyte drink
Avoid high-fructose juices or fizzy drinks if they bother your gut
The Takeaway
The best pre-workout meal is one that:
✅ Fuels you
✅ Feels good in your gut
✅ Keeps your blood sugar stable
If you're managing pre-diabetes or IBS, pre-workout nutrition doesn't have to be complicated — but it should be intentional.
Start small, pay attention to how your body feels, and adjust from there. And if you want personalized support? Let’s chat.