Eating enough can be harder than you think. Whether it’s due to work stress, lack of time, or a heatwave affecting your appetite, not getting enough fuel in throughout the day is relatively common – especially for women. Yet, over time, it can have far-reaching consequences, including reduced bone density, hormone disruption, and compromised immunity and performance. That’s why it’s vital we understand how to recognise the physical, mental, and emotional signs our body sends us when we aren’t nourishing it properly.
‘Not eating enough can trigger the body to conserve energy, leading to lower training output, feeling cold, and low mood. When you under-eat, blood sugar regulation becomes unstable, so energy crashes are more likely,’ says Leah de Souza-Thomas, a nutrition expert specialising in public health.
‘With too few calories to fuel basic processes, the body shifts into “conservation mode” and nutrient gaps, especially B vitamins, iron and magnesium, start to develop. This is the kind of bone-deep exhaustion where you’re dragging yourself through the day, that doesn’t improve with a good night’s sleep,’ she adds.
How many calories do women need?
It depends, says Souza-Thomas. ‘A useful ballpark range for active women to aim for is ~1,800-2,400+ kcal/day, with the higher end of that range reserved for heavier training days,’ she advises. For reference, the NHS recommends a daily average of 2,500kcal for men and 2,000kcal for women, and the National Institute of Healthcare and Excellence (NICE) puts that figure at around 20-35kcal/kg/day.
However, there are many factors at play: age, activity levels, body composition and metabolism, and training load and goals. ‘That said, under-fuelling is fairly common among active women, essentially not eating enough to support basic bodily functions and their training levels,’ adds Souza-Thomas.
‘It’s easily done. We’re all on tight, busy schedules, trying to fit it all in. And at a basic physiological level, it’s very easy to not feel like eating after training,’ she adds. Then there’s the deep-rooted issue of toxic diet culture: ‘We also need to remember that for many women, diet and weight-loss culture is so ingrained in our everyday thinking. It’s the background noise that nudges us to eat less, train harder, and very often misread low energy as a lack of willpower.’
‘In practice, I see women who have spent so long restricting calories that they’ve forgotten what it’s like to have normal energy levels,’ says Souza-Thomas. ‘They accept the fatigue they experience as just a part of life or worse still, getting older – a major bugbear of mine.’
There are several food groups she sees neglected. ‘Protein is getting a lot of airtime in marketing, but at intake, many clients’ food diaries show a shortfall in high-quality protein at breakfast and lunch, especially among those training at higher intensities,’ says Souza-Thomas. ‘Many women rely far too heavily on carbs and snacks – even the “high-protein” ones – too early in the day and as a result may not be getting enough quality protein to support hormone building, muscle repair or feeling full after meals.’
Complex carbs (slow-release carbs like whole grains, starchy vegetables and legumes) can also fall by the wayside, according to Souza-Thomas. ‘Most likely due to low carb/anti-carb trends, many women avoid or under-eat all carbohydrates, even whole grains and starchy veg,’ she says. ‘This may compromise performance and recovery and reduce intake of essential B vitamins (B1, B3 and B9/folate), which are important for energy production.’
Over time, if you’re not adequately fuelling your body, it ‘adapts to the nutrient shortfall it experiences by down-regulating energy output, which makes feeling good and maintaining a healthy weight harder, not easier.’
Does being tired all the time mean you’re not eating enough?
Tiredness can signal under-fuelling – but not always
It can be, says Souza-Thomas – but not always. ‘It’s important to rule out common causes of fatigue, eg, low B12 or iron, poor sleep, high stress, thyroid issues.’ However, if your tiredness is accompanied by poor recovery, increased delayed onset muscle soreness (DOMS) and brain fog, Souza-Thomas says your body is likely signalling that you’re not eating enough.
14 signs you’re not eating enough
Below, Souza-Thomas lists 14 ways in which the body signals it needs more fuel.
Common physical signals
- Persistent fatigue
- Hair loss or thinning
- Constipation
- Increased illness
- Sleep disturbances
- Slow wound healing
- Lighter/irregular periods or even loss of your period
Common mental and emotional signals
- Increased irritability often triggered by minor stressors that ordinarily wouldn’t have fazed you
- Brain fog
- Food preoccupation
- Low mood
- Anxiety and restlessness
- Loss of interest in activities you previously enjoyed
- Social withdrawal
What is RED-S?
If you train regularly, a serious risk of inadequate nutrition is Relative Energy Deficiency in Sport (RED-S), which can have lasting health implications, says Souza-Thomas. ‘80% of elite Australian female athletes had at least one symptom consistent with RED-S in this study, and it’s increasingly seen in recreational exercisers, too,’ she highlights.
‘These symptoms occur when energy intake doesn’t support the energy costs of exercise, growth and basic physiological functions, and the condition impacts bone density – increasing the risk of fractures – disrupts hormones, and compromises immunity and performance.’
For women, RED-S can often manifest in menstrual issues, like irregular or absent periods, and low bone mineral density. ‘If this happens in adolescence, it can impair peak bone mass, which increases the risk of osteoporosis or osteopenia later in life,’ explains Souza-Thomas, who strongly advises you consult your GP or a sports dietitian if you suspect RED-S.
Tips for eating more
Again, it sounds simple, but trying to eat more throughout the day – especially if you don’t work from home – can be difficult. Luckily, Souza-Thomas has some tips.
‘You can increase your calorie intake gradually without the overwhelm. One science-backed starting point is breakfast. Skipping it is often associated with lower intake throughout the day, which can perpetuate under-eating,’ says Souza-Thomas. Aim for three meals and one to two snacks daily and avoid fasted training, she adds.
‘High-quality protein should be distributed across every meal and snack to help with building muscle strength. Include carbs pre- and post-training and top up with energy-dense additions like tahini, olive oil, seeds, nuts, and avocados.’
According to Souza-Thomas, breakfast could include Greek yoghurt with fruit, oats and nut butter, eggs or tofu scramble with avocado and sourdough, or porridge made with protein powder, pumpkin seeds and blueberries. ‘And snacks might include protein pancakes, apple and nut butter smoothie, cottage cheese with cherries and seeds, and hummus and oatcakes.’
Adding seeds, olive oil and/or avocado to dinner is an effective way to boost calories without increasing overall portion size, advises Souza-Thomas, who also recommends eating with others when possible.
‘No lunch buddy? Recreate the vibe, plate up your food, sit at a table, have a check-in text back-and-forth with a friend, listen to a conversational podcast, or cafe-style background audio. Think social, not distracted, so no doomscrolling.’
