What's making me eat too much?

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1. Eyes v stomach

Is it your stomach or your brain that decides when you’ve had enough to eat? It appears that we don't select portions to match our energy needs – as a recent study shows, we underestimate how much we eat by one-third. That's 1,000 extra calories a day!

In studying eating behaviour, we've found that portion size is something we learn over time through daily encounters with different foods. We make complex judgements about our portions, balancing social, physical, economic and emotional dynamics every time we eat. However, we are also affected by other surprising influences.

2. Can we estimate calories to set portions?

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3. Which will fill you up the most?

How do labels affect our food choices? We think they give us useful information to make good decisions – can they impact how full we feel?

Extra chunky soup

Could be...

Chunky soup

Studies show that calories consumed as solids are considered more filling than liquids and people eat less later.

Low-fat soup

Probably not

Low-fat soup

People often compensate for foods marked low-fat or low-calorie by eating more or eating again soon after.

High-protein soup


High-protein soup

Meals that contain over 25% protein have been shown to increase the feeling of fullness. Meals with high-fibre pulses made people feel 31% more full.

Fuller for longer soup

Information matters

Fuller for longer soup

One experiment showed that women who were simply told an ordinary smoothie would keep them full for longer felt less hunger for 3 hours.

4. Which portion looks right to you?

Click the hand, then drag the player to add more food to your plates. Which portion of each food looks like an ideal size?

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We don’t judge a portion size by how many calories we need in each meal, as a proportion of the day. Our memories of previous meals – and whether they filled us up – dominate our idea of what a portion looks like before we take the first bite.

5. The effect of tableware

Click on the place setting to see how glasses, cutlery and plates affect how much you eat.

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6. I'll have what she's having

Is your portion size influenced by the company you keep? How often have you eaten out with friends and asked who’s having starters or puddings? We like to share food equally in company. But the effect can be even more subliminal.

The fat suit

One small study of 82 students (and one actress) showed the weight of our eating companions can affect us. In the study the actress ate lunch at a pasta and salad buffet with the group – only sometimes she wore a prosthetic suit that added 50lbs to her weight. No matter what she ate (more salad, less pasta, or vice versa) the people who ate with her consistently ate 30% more pasta and less salad when she was wearing the suit.

Eating to impress

Gender can also have an impact. Women in one study consistently chose lower-calorie foods from a cafeteria when eating with male companions than they did when they ate with female companions. This effect was greater if the group was bigger – women ate increasingly more in a large group of women but ate less and less if they ate with more male companions.

Of course, if you want to avoid overeating that doesn’t mean you should avoid dining with a particular size or sex of companion. The point is that many things affect how much we eat beyond the food itself, sometimes in a way that runs contrary to common sense. Understanding those influences is the best way to stick to your own portion size target.