Eating high-fat or high-sugar snacks can rewire brain circuits, creating lasting preferences. Photo / 123RF
We just can’t help ourselves – or can we? Here’s a little help from the experts in mastering our appetite.
If you regularly find yourself gripped by an unconquerable urge to reach into the cookie jar, then take comfort. Researchers from the German University of Tuebingen have uncovered the science behind a phenomenon familiar to women across the globe: cravings for junk food are simply unconquerable at certain times of the month.
Previous research has suggested that insulin in the brain helps to regulate the hunger sensation. This new study, however, found that the brain’s sensitivity to insulin fluctuates across different phases of a woman’s menstrual cycle, potentially explaining any powerful cravings in the second half of your cycle.
But gender is not the only factor that affects our susceptibility to junk food. Our personal history can play a role too, says Dr Saira Hameed, an NHS weight-loss expert and author of The Full Diet.
“My clinical observation is that we crave foods that we have an emotional connection with, and that association usually stems from childhood,” she says. “Think about a food you crave when you are sad or bored. You may well be able to trace a line back. If your mum made you hot buttered toast when you came home from school, for example, that association with love and comfort and connection will remain long after.”
Whatever you were raised on, you are unlikely, however, to crave healthy foods. “Carb-rich or sugary foods give us a feel-good high, activating the nucleus accumbens – the brain’s so-called ‘pleasure area’ – giving us a transient dopamine high,” she explains. “Carrots may taste good, but they don’t give us that same dopamine rush needed for an immediate pick-me-up.”
So are we at the mercy of our cravings? Not quite, explains Giles Yeo, a Cambridge University neuroscientist who studies brain control of body weight: “Cravings have genetic and environmental drivers. Your genes might predispose you to reach more frequently for sugary food. But if you are hungry, you will experience that craving feeling more powerfully. If you are stressed and super-busy, you’ll have less executive power available to put to use resisting your craving. In other words, you may be biologically susceptible to cravings, but your environment will affect your capacity to resist them.”
You can choose to interpret this either in a ‘glass half full’ or ‘glass half empty’ way, he suggests. “You can’t do anything about your genetic predisposition to cravings, but you can unpick the learnt and environmental elements.” So what can the experts tell us about specific cravings and how to curtail them?
Why?
“When we exercise, we fuel that activity by using a starch called glycogen that is stored in our liver and skeletal muscles,” says Dr Hameed. “Glycogen is the body’s quick-release carbohydrate store, it’s broken down into glucose and gives us energy for exercise. After exercise, these glycogen stores are depleted and the need to replenish them can result in us feeling the need to eat straight away.”
If your body is screaming for chips specifically, dehydration can also be the culprit, says nutritional therapist Lucy Miller. The fluids in your body carry vital minerals and electrolytes, including sodium (found in salt). These can become imbalanced due to dehydration. “When this happens, we can find ourselves craving salty foods.”
What to do?
“Reach for whole, natural foods like fruit and Greek yoghurt, which are unprocessed and will replenish glycogen stores with their natural sugar content,” suggests Dr Hameed. “Swap crisps for lower-salt sourdough crackers from Peter’s Yard and have with a savoury hummus dip,” suggests Miller. Drink water and if you want to actively replenish electrolytes after a work-out, avoid effervescent ones full of unnatural ingredients. Miller recommends Viridian Electrolyte Fix.
Why?
The most common reason for food cravings is blood sugar imbalance, says Miller. “When you consume foods high in sugar or refined carbs, they have a notable effect on your blood-sugar levels, prompting the release of insulin in order to transport the sugar from our bloodstream into our cells. Shortly thereafter, you may experience a swift decline in blood-sugar levels, which can result in increased cravings for more of the same.”
There’s more. Earlier this year, studies from Yale University showed that eating high-fat or high-sugar snacks can rewire brain circuits, creating lasting preferences for them.
What to do?
Prioritise eating whole foods that contain plenty of protein and fibre, suggests Miller: “It’ll keep you feeling fuller for longer and help to manage your blood-sugar levels.”
Why?
“Alcohol can lower blood sugar, making us feel that we need to eat something,” says Dr Hameed, “but it also lowers inhibitions and can make us more impulsive, so all our carefully-laid intentions about eating are side-tracked.” You might start the night eating salad and end it on a street corner, snaffling a shish.
What to do?
“Taking a good protein powder before you go out will help keep your blood sugar stable and leave you less likely to have these cravings,” says Miller. She recommends the Nuzest brand.
Why?
“In my clinic I’ve had several clients who crave diet cola every day, and I wouldn’t be surprised if some of that was mediated by their gut microbes,” says Dr Federica Amati, a medical scientist and nutritionist at Zoe, the personalised health company.
“Research is ongoing, but we think that our gut microbiome composition can impact the food choices we make, as the microbes themselves send chemical messages to encourage us to eat more of the food that benefits them. Cravings for foods can be a manifestation of that.” Some microbes love blueberries, but others – unfortunately for our waistlines – thrive off junk.
What to do?
“Swap your soda for kombucha,” she suggests. Fermented food and drink can bolster the gut microbiome, enhancing the diversity of microbes within it.
Why?
When we eat high-carb foods, the reward systems in our brains light up. The same thing happens when we eat high-fat foods. But when we eat foods that are high in both fat and carbohydrates, “they light up like a Christmas tree,” says Yeo.
This, he suggests, may be linked to the fact that few foods that occur naturally are high in both. The only exception? Breast milk. Could we be hard-wired to seek out such foods, in the interests of our early survival? “It’s a compelling narrative,” says Yeo, “though difficult to prove.”
What to do?
“You can substitute ice cream with healthier alternatives; simply blend fruit of your choice, such as banana, with plant milk and freeze in paper cups,” says Miller. For a high-protein alternative, “blend full-fat Greek yoghurt with fruit of your choice, plus a touch of honey, then freeze.”
Why
“Anecdotally, my female patients do report fluctuations in cravings depending on where they are with their cycle, with a propensity to want sweet foods such as chocolate in the few days before a period,” confirms Dr Hameed. In addition to the new findings about insulin and the brain, there are, she says, several biological mechanisms that might explain this.
“Oestrogen has a suppressive effect on appetite through affecting part of the brain called the hypothalamus, which controls the amount we eat, and levels of the hormone wax and wane with the menstrual cycle. The hormone progesterone peaks in the second half of the cycle and also impacts on appetite but has the opposite effect, tending to make us feel hungrier. Plus, low mood or reduced energy levels can obviously increase the attraction of a food pick-me-up,” says Dr Hameed.
What to do?
It is possible to change our comfort foods, suggests Dr Hameed, “by forming new associations which, with repetition, become wired in forming new brain connections.”
So ask yourself what might give you comparable – if not equal – pleasure to that super-sized Yorkie bar. Then make sure it’s available to you during the times of the month when you find yourself gripped by cravings. It needn’t be food, says Dr Hameed. “If the endorphin rush of exercise – and that can mean walking, gardening, basically movement – makes you feel good, make preparations in advance. Book dates in the diary to go walking with a friend, or go to the garden centre so you have plenty to get on with in the garden.”
It also helps to spring-clean your kitchen of sugary contraband. “If you were trying to give up alcohol, you wouldn’t keep a chilled bottle of white in the fridge,” says Dr Hameed.
Why?
Although pregnancy food cravings are relatively understudied, says Miller: “they are most likely due to the fluctuations in hormones, nutritional needs and a maternal instinct to protect the foetus from toxins.” A recent study suggested that the most common were for sweets, fruits, pickles, ice cream and pizza.
What to do?
Don’t worry too much, says Miller. The most important thing is to look after yourself, body and mind. That said: “Excessive gestational weight is emerging as a potential threat to the health and wellbeing of both women and children, so a well-balanced diet throughout pregnancy is important.” If sickness is playing a role in your cravings, Miller recommends the Cytoplan Pregna-Plan prenatal multi-vitamin and Bare Biology Mums and Bumps’ Omega-3 supplement.
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