HOW CAN DIET AFFECTS BLOOD SUGAR?

Diet has a direct and powerful effect on blood sugar levels because most of the food we eat—especially carbohydrates—is broken down into glucose. The type, amount, and timing of food all matter.

1. Carbohydrates: the biggest influence

Simple / refined carbohydrates

These raise blood sugar quickly and sharply:

• White rice, white bread, pastries
• Sugary drinks, sweets, desserts
• Sweetened cereals

🔺 Cause rapid spikes → more insulin needed → greater insulin resistance over time

Complex / whole carbohydrates

These raise blood sugar more slowly:

• Brown rice, oats, quinoa
• Whole-grain bread
• Sweet potatoes, legumes

✅ Slower digestion = steadier blood sugar

2. Glycaemic Index (GI) & Glycaemic Load (GL)

Glycaemic Index (GI)

• Measures how fast a food raises blood sugar
• High GI foods = rapid spike (e.g. white bread)
• Low GI foods = gradual rise (e.g. lentils)

Glycaemic Load (GL)

• Considers both GI and portion size
• Large portions of even low-GI foods can still raise sugar

👉 Best approach: low-to-moderate GI + portion control

3. Fibre: your blood sugar stabiliser

High-fibre foods:

• Slow glucose absorption
• Reduce blood sugar spikes
• Improve insulin sensitivity

Good sources:

• Vegetables
• Fruits with skin
• Whole grains
• Beans and lentils
• Nuts and seeds

Aim for 25–30 g fibre/day

4. Protein: reduces sugar spikes

Protein:

• Slows digestion of carbohydrates
• Reduces post-meal blood sugar rise
• Improves satiety (less overeating)

Good sources:

• Fish, eggs, lean poultry
• Tofu, tempeh
• Greek yoghurt, legumes

👉 Pair carbs with protein at every meal

5. Fats: type matters

Healthy fats

• Olive oil, avocado, nuts, seeds
• Slow digestion → steadier blood sugar

Unhealthy fats

• Trans fats, excessive saturated fats
• Worsen insulin resistance

6. Meal timing & portion size

• Large meals → bigger sugar spikes
• Skipping meals → blood sugar swings
• Late-night eating → poorer glucose control

✅ Better:

• Regular meal times
• Smaller, balanced meals
• Avoid sugary snacks between meals

7. Sugary drinks: the worst offenders

• Soft drinks, sweetened tea/coffee, fruit juice
• Liquid sugar enters bloodstream very fast

🚫 Replace with:

• Water
• Unsweetened tea
• Black coffee

8. Ultra-processed foods

Often contain:

• Hidden sugars
• Refined starches
• Unhealthy fats

📈 Increase blood sugar and insulin resistance even if “low fat”

9. Practical “plate method”

For stable blood sugar:

• ½ plate: Non-starchy vegetables
• ¼ plate: Protein
• ¼ plate: Whole-grain or low-GI carbs
• Add healthy fats

In summary

Diet affects blood sugar by:

• Controlling how fast glucose enters the bloodstream
• Influencing insulin sensitivity
• Preventing spikes and crashes