Always hungry? Giles Yeo on hunger, appetite and a fuller plate

If you're always hungry, first ask which kind of hunger it is. Real hunger usually has a cause in your day: long gaps, a light first meal, food that digests fast, short nights, or recent weight loss. Make the day more filling, earlier, and protect your sleep. If it's appetite, the fix is what's in front of you.

Giles Yeo is a comfort eater, and he knows it. "If I'm stressed, suddenly my face is in a bowl of noodles," he told the ZOE podcast. His wife, under the same kind of pressure, loses her appetite completely. The same stress hormone rises in both of them, he says, and they do opposite things (ZOE Science & Nutrition).

Yeo is Professor of Molecular Neuroendocrinology at the University of Cambridge, where he studies the brain circuits that drive eating and how genes act on them. His book Why Calories Don't Count argues that counting calories misses most of what matters (Orion). He doesn't dispute that losing weight needs less energy in than out. His point is where the difficulty lies: "The complexity is not in the physics of it, because that's the how, how you get to where you are. The complexity in terms of weight loss, weight maintenance is in the why."

And the why starts with hunger. "Why do some people appear to be hungrier than others all the time? Or how come some people take more to get full? And these are not imagined behaviors, they're just not." Below: how to tell hunger from appetite, why hunger gets louder when weight comes off, and four changes to your day, with what each study can and can't say.

Work out what kind of hungry you are

1. Tell hunger from appetite

Christopher Gardner, a nutrition professor at Stanford, puts the difference in two lines: "Hunger is a physiological state. Appetite is I could eat something." His example is dessert after a full dinner: "I don't have hunger for dessert. I have an appetite for dessert because you just showed me the dessert tray" (CNN Chasing Life, from 18:20).

Yeo describes appetite as a triangle with three points: how hungry you are, how full you are, and how rewarding the food is. "How hungry you and how full you are, are different circuits within the brain," he says, and pulling on one corner changes the others. When you're very hungry, plain food is enough: "a bit of bread, a bit of cheese, a bit of rice, it's like the simplest foods are the best." When you're full, only something very rewarding gets through, usually something high in sugar and fat. That's his explanation for the "dessert stomach."

In practice, before you eat between meals, ask: would a plain sandwich do? If yes, it's probably hunger. If only chocolate or chips will do, it's more likely appetite, set off by what's in sight or by a feeling. Our guides to portion control and emotional eating cover those. The sandwich question is our own shortcut built on Yeo's triangle, not a tested tool.

2. Expect hunger to get louder when weight comes off

Yeo is blunt about weight loss: "your brain absolutely hates it." It treats the loss as a threat and, without your noticing, pushes you to eat more, he says. The first pounds feel easy: "And then suddenly you plateau and then suddenly you're thinking, geez, I'm hungry." He adds that people differ in how strongly this happens: "not everyone will respond exactly the same way."

One study followed 50 adults with overweight or obesity through a 10-week weight-loss program on a very-low-energy diet. A year after the program, several appetite hormones were still different from where they started, and so was the hunger people reported (Sumithran et al., 2011). It's one study of one strict program.

Zachary Knight, a neuroscientist at the University of California, San Francisco, reached a similar view on Huberman Lab, after weighing how much the body slows down against how much appetite rises: "the increased hunger seems to be the main reason people find it so difficult to keep weight off" (Huberman Lab, chapter from 1:03:58). Some people, he added, don't experience it at all.

So if you've lost some weight and you're hungrier than you were, nothing has gone wrong with you. Our guide to the weight loss plateau goes further into that stage.

3. Find where the hunger builds in your day

In one US study, 189 adults in a year-long weight-loss program answered short phone surveys several times a day about how they felt and whether they had eaten something they hadn't planned (Forman et al., 2017). For each step up in hunger or in feeling deprived, the chance of a slip by the next survey rose by about a third. Tasty food close by raised it by about half. Slips came most often at home, in the evening.

That's a picture of how slips happen, not proof that hunger causes them. But it fits a familiar day: a coffee for breakfast, a few bites at the desk, and by seven the kitchen has taken over. As Yeo said on Science Vs: "If you are not hungry it is very easy to stop eating because you are not hungry. So there's no willpower, there's no challenge" (Science Vs). Our guide to eating at night picks up the evening itself.

Make the day more filling

Yeo's practical advice starts from fullness: "The easiest way to eat less is to feel fuller." The four changes below follow that idea, and none needs counting.

4. Give your first meal some protein and fiber, whenever it comes

In Yeo's account, food that takes longer to digest travels further down the gut and releases more fullness hormones. Protein is the slowest of the main nutrients, and fiber isn't digested at all, so foods high in both "naturally make you feel fuller." He didn't cite a study for it on the show.

The trials point the same way, more modestly. One review found higher-protein meals gave a modest feeling of fullness, but people didn't eat less at their next meal (Leidy et al., 2015); the review was funded in part by beef, dairy and egg industry groups. Across 24 trials with 1,063 adults lasting about 12 weeks on average, higher-protein diets led to a little more weight loss, under a kilogram (Wycherley et al., 2012). So protein tends to leave people a little fuller, and no one needs a gram target to use it.

The first meal doesn't have to be breakfast. In a review of 13 short trials in high-income countries, people asked to eat breakfast ate more over the day and weighed slightly more than people asked to skip it (Sievert et al., 2019). Timing still matters for hunger, though. In a trial in Aberdeen, Scotland, 30 adults with overweight or obesity ate the same food for four weeks with the biggest share of it, 45%, at breakfast, and four weeks with 45% at dinner. They lost the same amount of weight, and they felt less hungry through the day on the big-breakfast weeks (Ruddick-Collins et al., 2022).

In practice: eggs, yogurt, beans, cheese or tofu, with oats, wholegrain bread or fruit, whenever you first eat, ready the night before if mornings are rushed.

5. Don't let the gap run past about five hours

If the longest stretch of your day has no food in it, pack a snack you like the night before, a piece of fruit, a yogurt or a handful of nuts, and put it where you'll be when the gap gets long, often mid-afternoon. Five hours is our program's starting point, not a tested rule, built on the slips study above. If your gaps are already short, skip this step.

6. Fill half the plate with food that's heavy for its energy

Vegetables, fruit, soups and other water-rich foods add weight and volume to a meal without adding much energy. In a year-long trial at Penn State, 97 women with obesity were split into two groups, neither given a calorie target. One was advised to cut fat; the other to cut fat and eat more water-rich foods, especially fruit and vegetables. The second group ate about a quarter more food by weight, reported less hunger, and lost a little more weight (Ello-Martin et al., 2007).

Yeo's view of ultra-processed food fits here: most of it, he says, is low in protein and fiber, so it's "very quick to digest" and leaves you less full, though he thinks the label also sweeps in foods like yogurt with a bit of jam. Nothing has to be banned. A practical rule is to make vegetables or fruit about half of lunch and dinner, with some protein and whole grains, and keep frozen vegetables in for busy days. Our guide to the best diet for weight loss goes further.

7. Treat sleep as part of the plan

Short nights and hunger travel together. In a review of 11 small experiments, people ate more after their sleep was cut short, and burned no more energy (Al Khatib et al., 2017). The reverse was tested in Chicago: 80 adults aged 21 to 40 with overweight, who usually slept under six and a half hours, got either advice on sleeping longer or no change. Over two weeks the advised group slept about 1.2 hours more a night and ate noticeably less, with no diet prescribed (Tasali et al., 2022).

These are links measured over days and weeks, not proof that sleep alone changes weight. But if your nights are short, an earlier bedtime may leave you less hungry at no cost. Our guide to sleep deprivation covers how much sleep adults need.

Start with tomorrow's first meal

Yeo's comfort eating never went away; he organizes his life around it, he says, and some days it wins anyway. Hunger is biology, it differs from person to person, and it often gets louder just when you're making progress. What you can change is how empty the day runs. His summary for anyone who blames their genes is a card game: "you can win with a bad hand of cards and you can most certainly lose with a good hand of cards." If you do one thing, make tomorrow's first meal one with some protein and fiber, and pack a snack for the long gap. For the bigger picture, see how to lose weight sustainably and all-or-nothing eating.

To build this around your own day, try the 1h Protocol to Lose Weight Sustainably. Its free first chapter asks a few questions, finds your eating pattern (one of them is the day that runs on too little until the evening) and gives you one thing to do tomorrow. The full program is practical education and takes about an hour. It walks one day with you, from the first meal to bed, at your own times, and you leave with a page of the changes you chose, a plan for the "just one" moment, a card for your lock screen, a fourteen-day sheet, and days seven and fourteen in your calendar. You can write your own goal, a weight goal included; the program never sets a target, calories or a diet. Four short check-ins by email follow, on days 1, 7, 14 and 30. Start free

Frequently asked questions

Why am I always hungry?

Common reasons are long gaps, a first meal with little protein or fiber, food that digests quickly, short sleep, and recent weight loss, which raises hunger for many people (Sumithran et al., 2011). People also differ: Yeo says some are simply hungrier than others, partly through their genes. If it's appetite rather than hunger, what's in sight and how you feel matter more than what you ate.

What's the difference between hunger and appetite?

Hunger is your body's push to eat. Appetite is wanting food because it's there or looks good (CNN Chasing Life). Hunger responds to a more filling day; appetite responds to changing what's in front of you.

What is food noise, and is it just hunger?

"Food noise" is a popular term for constant, intrusive thoughts about food. Ania Jastreboff, an obesity physician and researcher, separates it from hunger: "A lot of people talk about food noise, which is different than hunger. It's appropriate to be hungry as humans." She describes food noise as "disruptive, persistent, intrusive" (ZOE Science & Nutrition). A less empty day quiets real hunger; for thoughts set off by food in sight or by feelings, changing your surroundings helps more. If eating still feels out of your control after two weeks, talk to someone you trust. Our program isn't for anyone pregnant or breastfeeding, or living with an eating disorder now or in the past.

Does protein keep you full?

A little. Higher-protein meals leave people modestly fuller, though they don't eat less at the next meal (Leidy et al., 2015). Some protein at each meal is a sensible habit; you don't need a target.

Is breakfast important for weight loss?

Not on its own. In short trials, people asked to eat breakfast ate more over the day and weighed slightly more than people who skipped it (Sievert et al., 2019). What matters for hunger is not arriving at the evening empty, whenever your first meal is.

Sources

This article draws on Giles Yeo's interviews on ZOE Science & Nutrition and Science Vs and his publisher's description of his book, Christopher Gardner on CNN Chasing Life, Zachary Knight on Huberman Lab, Ania Jastreboff on ZOE Science & Nutrition, and the studies listed below. ZOE is a company that sells nutrition products; its promotions were not used.

• Prof. Giles Yeo and the science of weight loss: Why calories don't count (podcast episode, ZOE Science & Nutrition, 2025)
• Obesity: Is It Your Fault? (podcast episode with Giles Yeo, Science Vs, 2017)
• Giles Yeo, Why Calories Don't Count (book, publisher page, 2021)
• Do Diets Really Work? (podcast episode with Christopher Gardner, CNN Chasing Life, 2024)
• Dr. Zachary Knight: The Science of Hunger & Medications to Combat Obesity (podcast episode, Huberman Lab, 2024)
• Should you take Ozempic? 5 things you need to know before starting GLP-1 drugs (podcast episode with Ania Jastreboff, ZOE Science & Nutrition, 2026; cited only for her description of food noise)
• Sumithran et al, Long-term persistence of hormonal adaptations to weight loss (study of 50 adults after a very-low-energy diet, abstract only, 2011)
• Forman et al, Ecological momentary assessment of dietary lapses across behavioral weight loss treatment (observational study, 189 adults in a year-long program, 2017)
• Ruddick-Collins et al, Timing of daily calorie loading affects appetite and hunger responses (randomized crossover trial, 30 adults, 2022)
• Sievert et al, Effect of breakfast on weight and energy intake (meta-analysis of 13 trials, 2019)
• Leidy et al, The role of protein in weight loss and maintenance (review, industry-supported, 2015)
• Wycherley et al, Energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets (meta-analysis of 24 trials, 1,063 adults, 2012)
• Ello-Martin et al, Dietary energy density in the treatment of obesity: a year-long trial (randomized trial, 97 women, 2007)
• Tasali et al, Effect of sleep extension on objectively assessed energy intake among adults with overweight (randomized trial, 80 adults, 2022)
• Al Khatib et al, The effects of partial sleep deprivation on energy balance (meta-analysis, abstract only, 2017)