10 Foods That Cause Weight Gain (and What to Eat Instead)

Often, yes, because the added sugar makes it a fast sugar hit. When manufacturers take the fat out of yogurt, it tastes like chalk. To make it palatable, they add massive amounts of sugar or fruit purees. While it might be low in calories, it can trigger a sharp blood sugar spike, which is why it scores high.

Yes, fruit juice raises blood sugar quickly even when it is fresh-pressed. Whole fruit contains fibre. Fibre acts like a net, slowing down how fast the sugar enters your bloodstream. When you juice a fruit, you rip out the net. In a small Lancet study, apple juice called for more insulin than whole apples with the same sugar and was followed by a dip in blood sugar (Haber et al., 1977).

Only slightly: whole grain is better than white bread, but barely. It is still a heavily processed carbohydrate that turns into blood sugar within minutes of digestion, sitting firmly in the high range on the glycemic index. Eating "healthy" whole-wheat toast every morning is a fast-digesting carbohydrate start to the day, not the protective swap most people assume.

Most commercial granola is: it is toasted oats bound with honey or syrup and dried fruit, which makes it mostly fast-digesting starch and sugar, and RealFoods scores it 8 out of 10. Often marketed with pictures of athletes and mountains, commercial granola is essentially broken down cake. It's toasted in honey, agave, or syrups, mixed with dried fruit (concentrated sugar), and delivers a heavy carbohydrate load that can set up a mid-morning hunger crash. Yogurt, toast, and granola all show up at breakfast, so start with the high insulin breakfast foods to swap.

Oats are starches. When you blend them into milk, you're drinking liquefied starch. Many commercial brands add sugar or use a chemical process to break down the oats into simple maltose sugars. An iced oat latte is often a disguised dessert.

Check the ingredients. While they boast "20g of protein" on the front, the back often reveals 25g of carbohydrates tied together with syrups, artificial sweeteners, and dates. That much fast-digesting carbohydrate can raise blood sugar and insulin quickly, even with the protein alongside it.

That vibrant green hue might come from spinach, but the taste comes from apple chunks, bananas, and sometimes pure fruit extracts. The bigger issue is how much fruit and juice fits in one cup, often more than you would eat whole in one sitting. Blending itself matters less than people think: in one trial, blended mango did not raise blood sugar more than whole mango (Redfern et al., 2017).

Similar to yogurt, when the fat is stripped out of dressing, it separates quickly and tastes acidic. Food companies add thickeners and sugar to restore the texture. Ironically, full-fat olive oil dressings help you absorb the nutrients from the salad and are far less likely to push insulin up.

A staple of the 1990s low-fat craze. They are essentially puffed starch with zero fibre or protein to slow down digestion. Eating rice cakes can produce a quick rise in blood sugar, and for some people a hunger crash not long after.

Unless you are running a marathon or completing an intense 90-minute training session, you do not need to restock your glycogen stores with a sports drink. Drinking these casually delivers flavoured liquid sugar directly into your bloodstream.