Episode 34: Why diets don’t work...and how to use weight loss science to your advantage

OnCore Nutrition - Two Peas in a Podcast

When it comes to dieting everyone is always looking for a quick fix.

Effectiveness of diets long term

Interesting study https://www.bmj.com/content/bmj/369/bmj.m696.full.pdf

• It looked at “Comparison of dietary macronutrient patterns of 14 popular named dietary programmes for weight and cardiovascular risk factor reduction in adults: systematic review and network meta-analysis of randomised trials”
• Randomised trials that enrolled adults (≥18 years) who were overweight (body mass index 25-29) or obese (≥30) to a popular named diet or an alternative diet.
• Outcome measures included change in body weight, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, BP (systolic blood pressure & diastolic blood pressure), and CRP at 6 and 12 month follow-up.
• 121 trials made the cut (21,942 patients) - huge study
• Dietary intervention group assessed based on macro breakdown were:
  • Low carb (e.g. Atkins, south beach, zone)
  • Moderate marcos (e.g. Biggest Loser, DASH, Jenny Craig, Mediterranean, Portfolio, Slimming World, Volumetrics, Weight Watchers)
  • Low fat (Ornish, Rosemary Conley)
• Control group
  • Control diets included: maintain usual dietary habits, dietary advice (eg, received brochures, dietary materials including dietary guidelines, or consultation with a professional dietitian by email or telephone), and low fat diet (≤30% fat with or without advice about lowering calories).
• Results:
  • Positive weight loss improvements at the 12 month follow-up diminished.
  • Improvements in cardiovascular risk factors largely disappeared except for Mediterranean diet for LDL reduction
  • Differences between diets are, however, generally trivial to small, implying that people can choose the diet they prefer from among many of the available diets to adhere to what works best for them.
• Bottomline: no matter if you like low carb, high carb, low fat, etc… diet’s are not effective in reducing weight and keeping it off.

Other large scale reviews confirm that diets simply don’t work

Grade A evidence - NHMRC Clinical Practice Guidelines For The Management Of Overweight And Obesity In Adults, Adolescents And Children In Australia

• Weight loss following lifestyle intervention is maximal at 6–12 months. Regardless of the degree of initial weight loss, most weight is regained within a 2-year period and by 5 years the majority of people are at their pre-intervention body weight.
• Our suggestion: The intervention should never stop!

Grade A evidence

• Modest weight loss improved CVD, T2DM risk factors and grade B evidence for sleep apnoea, joint issues, graed C for musculoskeletal problems, GI and urinary, self esteem, depression and QOL
• For adults who are overweight or obese, strongly recommend lifestyle change—including reduced energy intake, increased physical activity and measures to support behavioural change.
• 6 For adults who achieve initial weight loss, strongly recommend the adoption of specific strategies, appropriate to their individual situation, to minimise weight regain
• NHMRC Guidelines file:///C:/Users/Loz/Downloads/n57-obesity-guidelines-%20(1).pdf

Also Scientific research that ideal BMI for longevity is 25-30kg/m2

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4855514/

https://www.bbmt.org/article/S1083-8791(05)01413-8/abstract

Why don’t diets work?

A combination of physiology and psychology

For the physiology behind why it doesn't work Listen to Episode 18

Interesting paper here https://www.ncbi.nlm.nih.gov/pubmed/23911805?dopt=Abstract

Dieting cycle

Biology: (listen back to ep18)

• Short term:
  • Anyone who is below their set point (too thin for them) will experience many physiological symptoms, similar to that of starvation.
  • What is important to know is that it doesn't matter what weight you start at, but rather what is normal for you.
  • Experience feeling of extreme hunger, metabolism suppressed so your body burns less energy, muscles use less energy during PA, feel cold, lethargic and obsessive over food - normal sx’s of your brain saying ‘alarm bells, food is needed’
  • Biological pressure to restore body weight gets stronger as weight loss increases. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5764193/pdf/nihms904015.pdf
  • 
    
• Long term:
  • Some people will be heavier than when they started and others will develop disordered eating patterns

Psychological impact of dieting/weight stigma

• Disordered eating patterns -greater emotional eating, uncontrolled eating, and loss-of-control eating
• Body image and self esteem concerns
• Psychological stress
• Relationship breakdown
• Increased anxiety and depression

Summary

• Weight is not tied to health and health looks different to everyone
• Lifestyle habits predict health better than weight alone
• If a ‘diet’ has a start and an end point - it’s unlikely to work.
• There are some factors we don’t think of when it comes to health, e.g poverty, loneliness, hormones, low levels of physical activity.
• So much energy is wasted on trying to change weight, when we should focus on making other health improvements, e.g. exercise goal - start somewhere e.g. walking and progress, improved relationships with friends and loved ones, cook more
• https://www.jabfm.org/content/25/1/9.full
• Willpower as a finite resource

What you can actually do

• Reduce decision fatigue
• Do it for YOU - explore your deep reasons why. We do this quite a lot with our clients. It may present as ‘the wedding’ or ‘reunion’ or to ‘feel better in my jeans’ or ‘fit into that dress’ but why is that actually important to you? Will it impact your self efficacy?
• Use positivity. Research demonstrates that the feeling of success is more likely to drive positive change than actually achieving your goal
• Emotions create habits
• Micro goals - e.g change ‘exercise more’ to 2 squats per day, change ‘eat more veg’ to eat 1 carrot every 2 days. Can do more if you want, but you don’t have to. Beyond that is extra credit!
• Anchor your desired activities to things you already do, e.g. brushing teeth or showering.