9 Most Common Myths About Weight Loss That Will Keep You Fat


eating habits

Ever gone to the gym and noticed the women and men you KNOW have been regularly working out for years still carrying a big spare tyre around their middle?  Or observed the workmate who snacks on Twinkies and maintains a bean pole silhouette?

You’ve just sprung two of the commonly held myths about weight loss we are all so certain are true that we feel perplexed when the evidence before our eyes seems to contradict that universally held certitude.

The Twinkie Diet Works So before we get onto debunking weight loss myths in general, let’s just clear those two specific truisms: Yes it is possible to exercise regularly and still be overweight; and yes, you can live on a diet of Twinkies and still lose weight.


 Kansas State University nutrition professor Mark Haub proved that last year when he lose 27 pounds over two months on the Twinkie Diet – and lowered his ‘bad’ cholesterol and raised his ‘good’ cholesterol by 20 per cent while doing it….!

The point he wanted to make: if you eat fewer calories, (no matter how unhealthy the source) you will lose weight. Increasingly health professionals are becoming frustrated at the way science has disproved many widely held notions about weight loss, but the word is not getting through to the people who need it most.

As a recent Forbes magazine article, The 6 Weight Loss Tips That Science Actually Knows Work pointed out, some recent pieces in prestigious journals have sought to dispel the myths (1) surrounding weight loss and whether one specific diet is any better than other. (2) (It’s not, but more of that later).

We’ve supplemented and varied the Forbes list, to include some additional “myths” we think need exploding.

So here they are:

9 Myths About Weight Loss Science Shows Are Just Plain Wrong Weight Loss Myth

1 Exercise is More Important than Diet I’m sure we all have a sneaking fondness for the idea that if I give my body a really good workout, I can justify having that reward muffin at morning tea time.

Abs made in kitchen

 And we’ve been led to believe by many reputable authorities that the key to weight loss is regular exercise.  Sadly – although exercise is a good thing – the most important factor in losing weight is how many calories we put into our mouths – in a word – diet.

This also explains how our regular exercisers can retain an unhealthy pear shape.  If their morning workout is followed by too many celebratory lunches, they will still weigh more than they want.

“Decreasing food intake is much more effective than increasing physical activity to achieve weight loss. If you want to achieve a 300 kcal energy deficit you can run in the park for 3 miles or not eat 2 ounces of potato chips,” says Samuel Klein, MD at Washington University’s School of Medicine.

One year-long study with post-menopausal women which compared the benefits of diet alone, diet and exercise, or exercise alone for weight loss found of those who achieved a 10 per cent loss in weight:

  • The majority – 60% –  were in the combined  diet + exercise group
  • 42% – did it on diet alone
  • Only 3% did it on exercise alone

(The exercise consisted of 45 minutes of moderate-intensity physical activity 5 days a week, and the diet dropped calorie intake by 500 to 100 kcal daily.)(3) The reasons exercise alone is less effective are likely to be many, the experts suggest:

  • When we exercise we feel hungrier
  • We may feel tired and so over-compensate for the rest of the day by resting more

Weight Loss Myth 2

Cardio is the best form of exercise for fat loss

If you’re like me you feel particularly virtuous when you’ve done an especially long hike or run.  You may even feel a bit smug that you’ve done the very best for your body by giving your cardio vascular system a good oxygen blast. Not only have you got the endorphins going, but you’ve “taken out an insurance policy” against gaining an extra couple of pounds this week.

Man With Dumbbells

  But the Daily Telegraph reports there is growing opinion that suggests cardio vascular workouts are not the most effective way to stay slim.

Performance trainer Jean-Claude Vacassin suggests rather successful fat loss will be largely down to your diet, not your cardio approach.

Says Vacassin: “Plenty of people get themselves in great shape without doing any traditional cardio – some with absolutely no form of cardio training whatsoever. It’s one tool in your armoury, but it’s not the only way, and it’s certainly not the most efficient way.

“What works for one person will not always work for another so it’s impossible to say that one training method always trumps another for a specific goal.

But, if I were going to do a simplistic hierarchy of fat loss it might be:

1. Nutrition

2. Resistance training

3. Interval training

4. Steady cardio training

You’ll notice that nutrition comes first and traditional steady state cardiovascular training is last. It’s not that it’s not beneficial – of course it is – but in terms of effectiveness and efficiency Vacassin says he sees better results when people combine nutrition and resistance training.

A Duke University study which compared aerobics and weight training for weight loss found that after eight months the aerobics only group lost more weight, body fat and inches around the waist than the weight training only group. Only those who lifted weights gained muscle. (4)

Weight Loss Myth 3

You only need to do a little bit of exercise to get big benefits

The idea that taking the stairs instead of the elevator or getting out for ten minutes of walking now at lunchtime will make a difference may make you feel good, but sadly doesn’t hold up to close examination, say the experts.

work lunch

Reputable web sites and national health organisations publish this idea that small daily changes – walking for 20 minutes or eating two extra potato chips – can lead to long term benefits But the research does not support this idea, and in fact new recommendations for daily exercise are increasing recommended daily workout times to 60 minutes a day (3) or 150 – 250 minutes a week. (3)

The New England Medical Journal addressed this myth under the heading: Myth number 1: Small sustained changes in energy intake or expenditure will produce large, long-term weight changes.

The idea for this arose from studies from more than 50 years ago, based on experiments with men on very low calorie diets of below 800kcal daily. Calculations were based on a faulty model which failed to take into account how the body adjusts to changes in energy expended, the research shows.

As a result, predictions that a person who increases daily energy expenditure by 100 kcal by walking 1 mile (1.6 km) per day will lose more than 50 lb (22.7 kg) over a period of 5 years, were well off the mark. “The true weight loss is only about 10 lb (4.5 kg),assuming no compensatory increase in caloric intake, because changes in mass concomitantly alter the energy requirements of the body.”  

Weight Loss Myth No 4

Breakfast is the most important meal of the day

The idea that breakfast is the most important meal of the day is based on the assumption that missing breakfast leads to overeating later in the day, or seeking a “sugar high” mid-morning by snacking on something sweet and unhealthy.


 It also presumes that regular eating, compared with skipping meals, is protective against obesity. Two randomized, controlled trials that studied the outcome of eating versus skipping breakfast showed no effect on weight in the total sample.

However, the findings in one study suggested that the effect on weight loss of being assigned to eat or skip breakfast was dependent on baseline breakfast habits. (5 ) And another trial found men who skipped breakfast had a higher risk of coronary heart disease. (6)

So while it may not affect weight loss directly, having a regular breakfast still might be a good idea.

Weight Loss Myth No 5

Eating More Fruit & Vegetables Will Result In Weight Loss or Less Weight Gain

The assumption behind this idea is that if you eat more fruit and vegetables you’ll eat less of other things, leading to an overall benefit in weight loss as well as healthiness


 It is true that the consumption of fruits and vegetables has health benefits. However, when no other behavioral changes accompany increased consumption of fruits and vegetables, weight gain may occur or there may be no change in weight.(7)

Weight Loss Myth No 6

There’s a magic diet that will suit my metabolism and make it easy to lose weight Magic Diet The only “magical” component you need to make a diet work for you is to stick to it, say scientists. Numerous randomized trials have compared different diets (low-carb, low fat, Mediterranean) and they have found very small differences (less than a kg) and often inconsistent results.

When someone else tests it a year later they get slightly different results. Notes the Journal of the American Medical Association report: “The only consistent finding among the trials is that adherence—the degree to which participants continued in the program or met program goals for diet and physical activity—was most strongly associated with weight loss and improvement in disease-related outcomes.”(2)

The truth is all diets work if you stick to them.

Weight Loss Myth No 7  

If I could just cut out on snacking I’d lose weight Snack Assumption – if you snack, you still eat the same at main meals, so the calories you consume in snacks are inadequately compensated for in your regular meals. Hence the presumption is, snacking contributes to weight gain and obesity.

However randomized, controlled trials do not support this presumption.(8) Even observational studies have not shown a consistent association between snacking and obesity or increased BMI.

Weight Loss Myth No 8

If you lose weight slowly you’re more likely to keep it off

Research does not show any difference in the long term results from slow gradual weight loss and rapid loss. (9)

Slow Weight Loss

 Danish research which compared two groups who lost the same amount of weight – over 12 kgs – foundthere was no difference in the long term outcome whether the weight was lost rapidly or more slowly. And doctors suggest recommendation to lose weight more slowly might interfere with the ultimate success of weight-loss efforts, because many people feel strongly motivated to continue with their diet when they see a good result quickly.

Weight Loss Myth No 9

Having Sex is a Good Way to Lose Weight

Sad to say we’d love to tell you that having a robust sex life was going to do great things for keeping weight control as well, but the experts say this is also another myth.

Online tools like the Sex Calculator are one of many agents to push this popular idea that getting steamed up in the bedroom burns the same amount of calories as a vigorous bout of exercise.

The Sex Calculator site claims that a half-an-hour lovey dovey session will burn 150 calories, which is the equivalent of jogging for 15 minutes. But the authors of the Obesity Myths report argue claiming sex is good for weight loss is faulty logic.

Rather they say, “the energy expenditure of sexual intercourse can be estimated by taking the product of activity intensity in metabolic equivalents (METs), the body weight in kilograms, and time spent.

“That means that a man weighing 154 lb (70 kg) would, at 3 METs, expend approximately 3.5 kcal per minute (210 kcal per hour) during a stimulation and orgasm session. This level of expenditure is similar to that achieved by walking at a moderate pace (approximately 2.5 miles [4 km] per hour).

“Given that the average bout of sexual activity lasts about 6 minutes, a man in his early-to-mid-30s might expend approximately 21 kcal during sexual intercourse. “Of course, he would have spent roughly one third that amount of energy just watching television, so the incremental benefit of one bout of sexual activity with respect to energy expended is plausibly on the order of 14 kcal,” the report noted.  


1. Myths, Presumptions, and Facts about Obesity, Krista Casazza, Ph.D. et al., New England  Journal of  Medicine,  2013; 368:446-454 January 31, 2013 DOI: 10.1056/NEJMsa1208051 http://www.nejm.org/doi/full/10.1056/NEJMsa1208051

2.      A Call for an End to the Diet Debates, Sherry L. Pagoto, Bradley M. Appelhans, Journal of the American Medical Association, August 21, 2013, Vol 310, No. 7, 2013; 310(7):687-688. doi:10.1001/jama.2013.8601. http://www.nejm.org/doi/full/10.1056/NEJMsa1208051#t=articleTop

3.      Effect of diet and exercise, alone or combined, on weight and body composition in overweight-to-obese post-menopausal women, KE Foster-Schubert,1,2 CM Alfano,3 CR Duggan,1 L Xiao,1 KL Campbell,4 A Kong,1 C Bain,1 CY Wang,1,2 G Blackburn,5 and A McTiernan1,2 Obesity (Silver Spring), Aug 2012; 20(8): 1628–1638. Published online Apr 14, 2011. doi:  10.1038/oby.2011.76

4. Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults,Leslie H. Willis , Cris A. Slentz , Lori A. Bateman , A. Tamlyn Shields , Lucy W. Piner , Connie W. Bales , Joseph A. Houmard , William E. Kraus, Journal of Applied PhysiologyPublished 15 December 2012, Vol. 113 no. 1831-1837 DOI: 10.1152/japplphysiol.01370.2011, http://jap.physiology.org/content/113/12/1831

5.      Deleterious effects of omitting breakfast on insulin sensitivity and fasting lipid profiles in healthy lean women, Farshchi HR, Taylor MA, Macdonald IA. American Journal of Clinical Nutrition,  2005;81(2):388-396. http://ajcn.nutrition.org/content/81/2/388.full

And: Breakfast consumption affects appetite, energy intake, and the metabolic and endocrine responses to foods consumed later in the day in male habitual breakfast eaters, Astbury NM, Taylor MA, Macdonald IA. J Nutr 2011; 141(7):1381-1389.  http://jn.nutrition.org/content/141/7/1381

6. Skipping breakfast or eating late at night increases risk of coronary heart disease, 24-7-2013 • Cahill LE, Chiuve SE, Mekary RA And: Prospective Study of Breakfast Eating and Incident Coronary Heart Disease in a Cohort of Male US Health Professionals, Cahill LE, Chiuve SE, Mekary RA, et al. Circulation. 2013 Jul 23; 128(4):337-43. doi: 10.1161/CIRCULATIONAHA.113.001474 http://www.epccs.eu/d/169/skipping-breakfast-or-eating-late-at-night-increases-risk-of-coronary-heart-disease

  1. Effects of added fruits and vegetables on dietary intakes and body weight in Scottish adults, Whybrow S1Harrison CLMayer CJames Stubbs R. British Journal of Nutrition, 2006 Mar; 95(3):496-503.


  1. No consistent association between consumption of energy-dense snack foods and annual weight and waist circumference changes in Dutch adults, Hendriksen MA, Boer JM, Du H, Feskens EJ, van der AD Am, Journal of Clinical Nutrition, 2011;94(1):19-25, http://www.ncbi.nlm.nih.gov/pubmed/21613561

And:  No consistent association between consumption of energy-dense snack foods and annual weight and waist circumference changes in Dutch adults, Hendriksen MA1Boer JMDu HFeskens EJvan der A DL, American  Journal of  Clinical Nutrition, 2011 Jul;94(1):19-25. doi: 10.3945/ajcn.111.014795. Epub 2011 May 25. http://www.ncbi.nlm.nih.gov/pubmed/21613561

9. Randomised comparison of diets for maintaining obese subjects’ weight after major weight loss: ad lib, low fat, high carbohydrate diet v fixed energy intake, Toubro S, Astrup A, British Medical Journal, 1997;314(7073):29-34, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2676575/      

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