Workers who start the day with toast and jam, sugary cereals or pastries are more likely to feel shattered and lethargic by 11am than protein eaters, a new study by British Lion Eggs suggests.
The research, based on 2,000 UK adults, found 29% of sugary breakfast eaters reported feeling exhausted by mid-morning compared with 17% of protein eaters. They were also likelier to feel sluggish all day (29% versus 19%), unhappy (35% versus 29%) and unmotivated (38% versus 32%).
The blood sugar rollercoaster
“A breakfast high in free sugars or refined carbohydrates, but low in protein and fibre, may cause blood glucose to rise and fall more rapidly,” leading UK dietitian Nichola Ludlam-Raine told the Express.
“Although this doesn’t affect everyone in the same way, some people may notice a dip in energy, concentration or mood later in the morning,” she explained. Experts say the culprit is blood sugar volatility: a sweet breakfast causes glucose to spike, then tumble, a rollercoaster the brain feels as fatigue, fog and fretfulness.
Mid-morning slump and workplace naps
The study showed 21% of sugary breakfast eaters regularly experienced a mid-morning slump, while 41% admitted to struggling to concentrate during morning meetings. One in five (21%) confessed to taking naps at work – in their car, an empty meeting room or even the office toilets.
Protein keeps energy steady
By contrast, workers choosing protein-rich breakfasts were more likely to report feeling energetic (29% versus 19%), happy (35% versus 29%) and motivated (38% versus 32%). Protein, by contrast, is the steadying anchor: it helps slow the release of glucose into the bloodstream, blunting spikes and keeping you fuller for longer.
Ludlam-Raine says sugar doesn’t directly cause anxiety, but fluctuations in blood glucose may produce sensations that feel similar in susceptible people. “If blood glucose falls quickly or becomes too low, the body may release hormones such as adrenaline to help restore it. This can cause symptoms including shakiness, sweating or a racing heartbeat, which may resemble anxiety. Pairing carbohydrates with protein, fibre and healthy fats can support steadier energy and help make breakfast more satisfying,” she said.
What the dietitian recommends
“Choosing a breakfast that contains protein and fibre, while keeping free sugars relatively low, can support steadier energy and help you feel fuller for longer,” Ludlam-Raine said. “Eggs provide high-quality protein as well as choline, a nutrient involved in normal brain and nervous-system function.”
“Some eggs, particularly omega-3-enriched varieties, also provide DHA, making them a nutritious choice before a busy morning,” she added. The research also found 51% of workers want to improve their energy levels through simple lifestyle changes, while almost a quarter (23%) now track their protein intake using apps.
10 unhappy breakfasts
According to the dietitian, these sweet options are most likely to cause a mid-morning crash:
- Toast with butter and jam
- Toast with chocolate spread
- Porridge topped heavily with honey, syrup or jam
- A bowl of high-sugar, low-fibre cereal
- Sugary granola served without a protein source
- Pain au chocolat
- Croissant with jam
- Cinnamon roll
- Pancakes with syrup
- French toast topped with syrup, but no fruit or protein-rich accompaniment
10 happy breakfasts
For a steadier morning, she recommends swapping to protein-focused meals such as:
- Vegetable omelette with wholegrain toast
- Dippy egg with wholegrain/sourdough and asparagus soldiers
- Poached eggs with spinach on a wholegrain muffin
- Smashed avocado and egg on wholegrain toast
- Greek yoghurt/kefir with berries, nuts and seeds
- Scrambled eggs with tomatoes and wholegrain toast
- Protein oats or porridge with kefir, fruit and seeds
- A high-protein smoothie containing Greek yoghurt/kefir, fruit and oats
- Overnight oats with chia seeds and peanut butter
- Cottage cheese with banana and pumpkin seeds
For those who regularly experience an 11am energy slump, Ludlam-Raine says breakfast could be the simplest place to start. “If you regularly experience an energy dip by 11am, it may be worth looking at your breakfast,” she said. “Swapping a high-sugar option for a meal built around protein and fibre may help support steadier energy, better concentration and a more stable mood throughout the morning.”
