Willpower is a mental muscle that you can train. Those who do so are more likely to lead happy and successful lives

In the smart restaurant of a very smart hotel in the West End of London, Roy F Baumeister, eminent American social psychology professor, orders a lunch of fish and chips, and then decides not to eat the chips. "I won't eat something that's not good for me unless it's absolutely perfect, and it's going to give me real pleasure," he says. "I'm afraid ... Well, it just didn't look like these were going to do either."

What willpower, you might say. You'd be right; the chips looked pretty good. But Baumeister is also, coincidentally, a leading authority on that very subject, and has just published a smash-hit book on it with New York Times science writer John Tierney.

Willpower: Rediscovering Our Greatest Strength distills three decades of academic research (Baumeister's contribution) into self-control and willpower, which the Florida State University social psychologist bluntly identifies as "the key to success and a happy life".

The result is also (Tierney's contribution) readable, accessible and practical. It's an unusual self-help book, in fact, in that it offers not just advice, tips and insights to help develop, conserve and boost willpower, but grounds them in some science.

Willpower is, Baumeister argues over lunch, "what separates us from the animals. It's the capacity to restrain our impulses, resist temptation – do what's right and good for us in the long run, not what we want to do right now. It's central, in fact, to civilisation."

The disciplined and dutiful Victorians, all stiff upper lip and lashings of moral fibre, had willpower in spades; as, sadly, did the Nazis, who referred to their evil adventure as the "triumph of will". In the 60s we thought otherwise: let it all hang out; if it feels good, do it; I'm OK, you're OK.

But without willpower, it seems, we're actually rarely OK. In the 60s a sociologist called Walter Mischel was interested in how young children resist instant gratification; he offered them the choice of a marshmallow now, or two if they could wait 15 minutes. Years later, he tracked some of the kids down, and made a startling discovery.

Mischel's findings have recently been confirmed by a remarkable long-term study in New Zealand, concluded in 2010. For 32 years, starting at birth, a team of international researchers tracked 1,000 people, rating their observed and reported self-control and willpower in a different ways.

What they found was that, even taking into account differences of intelligence, race and social class, those with high self-control – those who, in Mischel's experiment, held out for two marshmallows later – grew into healthier, happier and wealthier adults.

Those with low willpower, the study discovered, fared less well academically. They were more likely to be in low-paying jobs with few savings, to be overweight, to have drug or alcohol problems, and to have difficulty maintaining stable relationships (many were single parents). They were also nearly four times more likely to have a criminal conviction. "Willpower," concludes Baumeister, "is one of the most important predictors of success in life."

So how can we improve ours? Baumeister's big idea, now borne out by hundreds of ingenious experiments in his and other social psychologists' labs, is that willpower – the force by which we control and manage our thoughts, impulses and emotions and which helps us persevere with difficult tasks – is actually rather like a kind of moral muscle.

Like a muscle, it can get tired if you overuse it. Exercising willpower, but also making decisions and choices and taking initiatives, all seem to draw on the same well of energy, Baumeister has established. In experiments, he found that straight after accomplishing a task that required them to restrain their impulses (saying no to chocolate biscuits, suppressing their emotions while watching a three-tissue weepy), students were far more likely to underperform at other willpower-related jobs such as squeezing a handgrip or solving a difficult puzzle.

"The immune system also dips into the same pot, which is big, but finite," says Baumeister, "and, we are pretty sure, so does women's premenstrual syndrome. Having a cold tends to reduce your self-control, and PMS does the same. We get cranky and irritable, but it's not that we have nastier impulses – it's that our usual restraints have become weakened."

So best avoid trying to do too many things involving mental effort at the same time, or if you're ill. As with a muscle, though, you can train your willpower. Even small, day-to-day acts of willpower such as maintaining good posture, speaking in complete sentences or using a computer mouse with the other hand, can pay off by reinforcing longer-term self-control in completely unrelated activities, Baumeister has found. People previously told to sit or stand up straight whenever they remembered later performed much better in lab willpower tests.

The final way in which willpower resembles a mental "muscle" is that when its strength is depleted, it can be revived with glucose. Getting a decent night's sleep and eating well – good, slow-burning fuel – is important in the exercise of willpower, but in times of dire need a quick shot of sugar can, according to Baumeister's lab tests, make all the difference.

(This is, of course, something of a problem for crash dieters, who basically need to eat in order to summon up the willpower not to eat. Indeed some very strong impulses, such as the behaviour often exhibited by males in possession of an erect penis, can sometimes prove completely resistant to willpower, even after the ingestion of a can of Coca-Cola.)

Baumeister cites a "very impressive demonstration" of the glucose argument: in a study published last year, researchers found that Israeli judges making the difficult and sensitive decision of whether or not to grant parole opted to do so in roughly 65% of cases after lunch, and hardly ever just before.

Baumeister's top willpower tips: Build up your self-control by exercising it regularly in small ways. Learn to recognise signs that your willpower may be waning. Don't crash diet. Don't try to do too much at once. Establish good habits and routines that will take the strain off your willpower. Learn how to draw up an effective to-do list.

Don't put yourself in temptation's way, or if you can't avoid it, make it harder for yourself to succumb. Use your willpower actively: plan, commit, and do so (like members of religious communities) publicly. "People with low willpower," Baumeister says, "use it to get themselves out of crises. People with high willpower use it not to get themselves into crises."

Much of this, of course, is in the book. You may even learn how to say no to chips.

Handel, who supported the initial decision to cut off funds, said it was 'best for Komen's future and the women we serve'

An executive with Susan G Komen for the Cure has resigned after a dispute over funding for Planned Parenthood and its providing of abortions, according to a letter obtained by the Associated Press.

Karen Handel, the vice-president for public policy for Komen, told officials that she supported the move to cut off funding for Planned Parenthood. She said the discussion started before she arrived at the organisation and was approved at the charity's highest levels.

Handel has been openly opposed to abortion. Planned Parenthood provides a range of women's health care services, including abortions.

"I am deeply disappointed by the gross mischaracterisations of [Komen's] strategy, its rationale, and my involvement in it," Handel said in her letter. "I openly acknowledge my role in the matter and continue to believe our decision was the best one for Komen's future and the women we serve."

Handel had supported a decision that Komen announced last week to exclude Planned Parenthood from future grants for breast-cancer screenings because it was under government investigation. The charity cited a probe launched by a Florida congressman at the urging of anti-abortion groups.

The breast cancer charity reversed course after its decision created a three-day firestorm of criticism. Members of Congress and Komen affiliates accused the group's national leadership of bending to pressure from anti-abortion activists.

Komen's founder and CEO, Nancy Brinker, denied the decision was driven by pressure from anti-abortion groups.

Until Tuesday, Handel had publicly kept silent about her role in the dispute.

A source with direct knowledge of decision-making at Komen's headquarters said the grant-making criteria were adopted with the deliberate intention of targeting Planned Parenthood.

According to the source, a driving force behind the move was Handel, who was hired by Komen last year after losing a campaign for governor in Georgia in which she stressed her anti-abortion views and frequently denounced Planned Parenthood.

Consultant investigating UK response to French PIP scandal warns committee of 'huge differences in levels of responsibility'

Surgeons who come to Britain for short periods of time to perform breast implant operations are putting patients at risk because they are less likely to provide satisfactory aftercare, MPs have been warned.

Simon Withey, a consultant plastic surgeon on the government's steering committee looking into standards following the PIP breast implant scandal, told the House of Commons health select committee some surgeons working for private clinics were peripatetic and employed part-time..

"Their engagement with clinical governance issues is perhaps not as strong as it might be," he said, adding there were "huge differences in levels of responsibility and record-keeping across the private sector".

Withey said surgeons in private cosmetic clinics may have had cheaper implants imposed on them by managers. PIP (Poly Implant Prothèse) products were sold at a third, a fifth or even a tenth of the cost of other implants.

However, Withey said surgeons had no reason to believe they were sub-standard until March 2010, when the French authorities announced an impromptu inspection had revealed the PIP implants were filled with industrial grade silicone intended for mattresses, not medical grade.

Sir Kent Woods, chief executive of the Medicines and Healthcare Products Regulatory Authority (MHRA), said the body had warned healthcare professionals not to use the PIP implants in March 2010.

"We used every route available to us to get the information out to where it was needed, but I can't honestly say that no PIP implant was moved out of store and into the operating theatre after that date," he said.

Barbara Keeley, MP, one of the members of the committee investigating the PIP scandal and wider issues relating to the cosmetic surgery industry, asked why the MHRA had told surgeons but not informed women of the problem.

"We're not in a position to do that because we don't have the identities of the patients," said Woods. "We can only go through the general media and the profession. We made every effort to put that information out at that time."

Keeley suggested these efforts had been ineffective and that women had not known the implants were substandard until the French authorities announced in December that women ought to have them removed, resulting in massive press attention there and in the UK.

"I think it is important to convey that there is a pool of women who are very, very anxious," she said. Some had sought help from the clinic where they had the operation but it had been taken over by a firm that refused any responsibility, she added. "Women are being spurned by receptionists in clinics unless they can come up with the money for a scan," she said.

NHS medical director Sir Bruce Keogh told the committee: "Some private clinics are failing to meet their duty of care."

For decades, Katherine Baldwin has worried about her thinning hair. Learning about androgenetic alopecia has helped her come to terms with her hair loss and take control of her treatment

Far from being my crowning glory, my hair has been the bane of my life. But one question has always plagued me: is my problem on my head, or in my head? While I've suspected my hair has been thinning for decades, few people ever believed me and at times I even doubted it myself.

There were years when my hair seemed fuller, when I'd scrunch it into ringlets and delight at its apparent thickness. At other times, particularly in my 30s, I'd fret over the wispy strands at the front of my head or when I saw too much scalp in the mirror.

My friends always reassured me I had a good head of hair. Most of the GPs I saw reacted the same, despite my tears and protestations. I had no bald patches or visible gaps so they'd put it down to stress or would test my iron and thyroid levels, which appeared normal.

Some of my hair loss over the years is easily explained. I developed an eating disorder and recall gathering clumps of hair off my pink bedroom carpet when I was under-eating in my teens.

Weight loss, low iron levels, poor diet and stress, along with thyroid and hormonal imbalances, can all cause hair to fall, trichologists say. Hair needs a healthy diet and a well-functioning endocrine system to flourish.

But diffuse hair shedding linked to weight, anaemia, diet or thyroid problems is temporary, according to Glenn Lyons, the clinical director at the Philip Kingsley Trichological Clinic in London. The hair follicle isn't damaged and the hair grows back automatically or once an imbalance is addressed.

The same goes for hair loss after childbirth or following cancer treatment – in most cases hair is restored. Even with alopecia areata, the sudden hair loss experienced by TV presenter Gail Porter that leaves bald patches, hair often grows back, although the problem can recur.

There is another type of female hair loss, however, that is less dramatic and less visible, but can be incredibly distressing. The hair thins gradually, often over decades, around the top frontal area and extending back to the crown. It can start at any age, is progressive and inherited.

"Genetic hair loss is the only hair loss in which the follicle gradually gets smaller and finer and producers smaller and finer hair until it stops altogether and then you get the thinning," says Lyons.

"It has a massive psychological impact on women because they're balding and thinning in a similar way to the men," adds Lyons, who sees women in their teens to their 80s with the condition. "There isn't a week goes by when we don't get women in tears in here. It affects self-esteem, confidence, quality of life and relationships."

Androgenetic alopecia, as the condition is known, is male hormone-related but isn't caused by too much testosterone. Instead, the hair follicles become sensitive, due to a genetic predisposition, to normal levels of male hormones in a woman's body.

But female hair loss is complex and Dr Hugh Rushton, a Harley Street trichologist, says 72% of women with male hormone-related hair loss are also iron deficient: "The key is to get an accurate diagnosis and to eliminate all other potential factors."

Stress can exacerbate genetic hair loss since the adrenal or stress glands secrete male hormones into the body, says Lyons. Polycystic ovaries can also accelerate the condition, and genetic hair loss will worsen in menopause unless treated as oestrogen levels drop.

I've had some ovarian cysts and have suffered with erratic eating, low iron and stress. But I always suspected there was something more to my thinning hair. The idea that it's genetic is finally making sense.

My mother's hair has been thinning for years, and her mother's did too. The gene can be passed down by either or both parents, and it can affect just one sibling – my brother has a great head of hair.

Fortunately for women, female pattern baldness is less severe than the male variety.

Lyons treats patients with scalp drops that aim to stop male hormones or androgens from damaging the follicles. For some women, trichologists recommend oral contraceptives, but only those with anti-androgens. Some contraceptives exacerbate hair loss, as do some hormone replacement therapies.

Dermatologists may prescribe the over-the-counter drug minoxidil for the scalp, but Lyons says lotions need to contain anti-androgens to fight genetic hair loss.

The correct treatment can restore some of the hair if the follicles are still alive but if they've died, the hair won't grow back, experts say. Existing hair can be preserved, however. The key, for the sake of a woman's sanity and self-esteem, is to catch the condition early – some women can lose up to half their hair before they even notice.

In my case, it's clear I've lost some of my hair for good. I have to keep it short, it feels fine and wispy and I can see too much scalp on the top. But perhaps I can do something about what's left. And even if I am losing my hair, at least now I know I'm not losing my mind.

Hair loss facts

Telogen effluvium – general shedding from all over the head. We typically lose some 100 hairs a day but sometimes shedding accelerates due to stress, illness, medication or hormones. Hair generally grows back within six months.

Androgenetic alopecia – in women, hair generally thins in the top, frontal area, just behind the hair line, but stays thick at the back. An enzyme causes conversion of the male sex hormone testosterone to another hormone, dihydrotestosterone (DHT), causing the hair follicles to produce thinner hair until they stop.

Alopecia areata – an autoimmune disease that affects up to 2% of the population. It causes round patches of hair loss and can lead to total baldness. In many cases, the hair regrows.

There are about 50 different hair loss disorders among men and women. For more information, visit nhs.uk/conditions/hair-loss.

• National Hair Loss Awareness Week is promoted by the Institute of Trichologists and runs until 6 February