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How often do you see fitness influencers sharing the virtues of exercise for creating fracture-proof bones, just as they do for rippling, strong muscles? Not so much. But we should all worry about losing bone strength given it’s almost inevitable as we age. And getting older isn’t the only risk factor for bone problems.
What we eat – or, more specifically, what we don’t – also impacts our bone health, a reality currently being faced by 38-year-old actor and presenter Jameela Jamil. She recently shared her experience with premature weakening bones on Instagram, saying: “I have been in a lot of pain lately and it turns out 20 years of dieting has hurt my bone density.”
In a world where we are constantly told that losing weight at any cost is a positive, experts praised Jamil’s post for raising awareness about the side effects of long-term calorie restriction. “Nobody tells us about the intense long term potential impact of speed weight loss from highly restrictive diets,” Jamil followed up in another post.
For Renee McGregor, a leading sports dietitian and eating disorder specialist, this isn’t news. “Sadly, in my clinic, I have seen 21-year-olds with severe osteoporosis, worse than you would see in 80-year-olds [as a result of under-eating],” she tells the i. “There are a number of reasons that not eating enough or dieting can impact bone health. Firstly the low energy intake will mean nutrient deficiencies, particularly of bone-supporting nutrients like protein, calcium and vitamin D, even those who take supplements.
“Most importantly, when someone is in severe restriction, even if their weight is not super low, the body switches on compensatory behaviours which down-regulate [reduce] biological processes, including the production of reproductive hormones like oestrogen and testosterone.”
This down-regulation is because periods and child rearing are expensive energy processes that aren’t essential in the short-term to keep us alive. So, instead of pumping out sex hormones, the body directs the little energy it receives towards keeping the heart beating and lungs breathing.
But missing out on these hormones has consequences. “These hormones also have a big part to play in bone health and also support the absorption of bone-supporting nutrients like vitamin D and calcium. So the longer your hormones flatline, the more potential damage to your bone health,” explains McGregor.
Exactly how long it takes from cutting calories to your bone health declining varies. “Around 70 per cent of our bone health is genetic, so if you are someone who genetically has a lower bone density then you are at higher risk of this becoming a problem sooner. But in general, we know that, in women, missing just three periods (which can happen as a result of the reduced hormones) is sufficient to start to have negative consequences to bone health,” says McGregor.
And despite bone health being important for everyone, it’s women who are particularly at risk here, given they are most likely to be targeted by diet culture and restrict their calories, and their bone mass has a sharper decline with age due to the menopause.
Indeed, researchers from the Department of Biological Sciences at Ohio University also found that just five days of low-energy intake in women led to an 11-12 per cent reduction in bone formation markers which researchers said, if left to continue, may lead to irreversible reductions in bone mineral density.
“Poor bone health leads to a condition known as osteopenia first and in worst cases, osteoporosis,” explains McGregor. Osteoporosis is one of the leading causes of fractures and the fourth-greatest cause of premature death, according to the Royal Osteoporosis Society, and the risk of fracture increases up to three times for every 10 percent drop in bone density.
How to protect your bones
The first way to improve most elements of our health, but especially regarding our bones, is to eat enough. “The best thing you can do for your bones is to ensure good energy intake – particularly of carbohydrates – to maintain your menstrual cycle in women and testosterone levels in men,” says McGregor. Ideally, focus on wholefood carbohydrates, as diets heavy in high-GI carbs (like potatoes and white bread) are also linked with reduced bone mass.
However, for people who are underweight or exercising regularly, easy-to-digest carbs are an important way to increase calorie intake. Eating too much is not ideal, either.
This is not to say you can’t make physical changes to your body. “If you are someone who legitimately needs to lose weight for health reasons, then the best way to avoid damage to bone health is to ensure small deficits and a more sustainable weight loss which does not disrupt hormonal health,” says McGregor. Nutritionist Rhiannon Lambert, author of The Science of Plant-Based Nutrition (published in June), says: “Fracture risk is lower in obesity but it is associated with reduced bone mass turnover, so bone health suffers in those who are both underweight or overweight.”
There is no one-size-fits-all when it comes to finding the perfect middle ground of eating “enough”. In the research, a low-energy state is defined as under 30 calories per kilo of fat-free mass a day, but working out muscle and fat percentages isn’t necessary (or healthy) for everyone. In general, the NHS recommends 2,000 calories for women and 2,500 calories for men, while very active individuals require more.
“Although I always recommend a food-first approach, a vitamin D supplement is recommended to every adult in the UK between the end of September and April, at a dosage of 10 micrograms per day,” adds Lambert. Calcium, on the other hand, can not be supplemented to make up for a low-nutrient diet. “Calcium supplements have been prescribed for many years to people at risk of osteoporosis. However, the science backing up whether they truly help isn’t necessarily there.
“Additionally, some research has found that calcium supplementation of more than 1000 mg per day may actually have some pretty nasty side effects including gastrointestinal symptoms, kidney stones, as well as – on the more severe side – a potential risk in the development of heart disease,” says Lambert. “It is recommended that calcium is derived from the diet as much as possible, and I highly recommend you prioritise dietary sources over supplements unless you have been told by a healthcare professional that you must take calcium supplements.”
To maintain strong and healthy bones, adults should eat 700mg of calcium increasing up to 1000mg for anyone who already has osteoporosis. People at other life stages or who have other medical conditions may need altered amounts. “To put that into context, you can get 222mg of calcium from a single 30g serving of cheddar cheese,” says Lambert. Other sources of calcium in your diet include yoghurt, almonds, dairy, fish with bones, and green leafy vegetables (not including spinach).
As well as diet, weight-bearing exercise is another one of the most important ways we can strengthen our bones. Just like with our muscles, bones grow stronger when broken down under load, with a one-year weight training programme in older women leading to a 5.3 percent increase in bone mineral density (controls who did no exercise saw a decline of 3 per cent).
“Resistance training can support bone health – but only when someone is not in a severe deficit or underweight,” says McGregor. The Journal of Bone and Mineral Research published a study in 2019 that looked at calorie restriction and exercise in mice to find that mild calorie restriction – around a 30 per cent reduction in daily intake – reduced bone quality and declined even further when diet was paired with exercise.
“Bone activity is at its highest immediately post-exercise, so ensure a good intake of carbohydrates and protein immediately after training so as to not further compromise bone health,“ says McGregor.
And, as Jamil says, “no compliment I have ever received is worth the pain and regret of what happens to your body when you do extreme things for fast results.”
