But on its own, “BMI [body mass index] remains a strong independent risk factor” for severe COVID-19, according to several studies that adjusted for age, sex, social class, diabetes, and heart conditions, says Naveed Sattar, an expert in cardiometabolic disease at the University of Glasgow. “And it seems to be a linear line, straight up.”
For starters, the blood of people with obesity has an increased tendency to clot—an especially grave risk during an infection that, when severe, independently peppers the small vessels of the lungs with clots
Immunity also weakens in people with obesity, in part because fat cells infiltrate the organs where immune cells are produced and stored, such as the spleen, bone marrow, and thymus, says Catherine Andersen, a nutritional scientist at Fairfield University. “We are losing immune tissue in exchange for adipose tissue, making the immune system less effective in either protecting the body from pathogens or responding to a vaccine,” she says.
The impact extends to the 32% of people in the United States who are overweight. The largest descriptive study yet of hospitalized U.S. COVID-19 patients, posted as a preprint last month by Genentech researchers, found that 77% of nearly 17,000 patients hospitalized with COVID-19 were overweight (29%) or obese (48%). (The Centers for Disease Control and Prevention defines overweight as having a BMI of 25 to 29.9 kilograms per square meter, and obesity as a BMI of 30 or greater.)
According to a recent study, obesity increases the risk of dying of Covid-19 by nearly 50%. Governments around the world are now hoping to encourage their citizens to lose weight. But with so much complex and often contradictory diet advice, as well as endless food fads, it can be hard to know what healthy eating actually looks like.
How many pieces of fruit and vegetables should you eat a day? Will cutting out carbs help you lose weight? Is breakfast really the most important meal of the day? Speaking to Tim Spector, professor of genetic epidemiology at King’s College London about his new book Spoon-Fed, Madeleine Finlay asks why we’re still getting food science wrong, and explores the current scientific evidence on snacking, supplements and calorie labels.
Tim Spector is a Professor of Genetic Epidemiology and Director of the TwinsUK Registry at Kings College, London and has recently been elected to the prestigious Fellowship of the Academy of Medical Sciences. He trained originally in rheumatology and epidemiology. In 1992 he moved into genetic epidemiology and founded the UK Twins Registry, of 13,000 twins, which is the richest collection of genotypic and phenotypic information worldwide. He is past President of the International Society of Twin Studies, directs the European Twin Registry Consortium (Discotwin) and collaborates with over 120 centres worldwide. He has demonstrated the genetic basis of a wide range of common complex traits, many previously thought to be mainly due to ageing and environment. Through genetic association studies (GWAS), his group have found over 500 novel gene loci in over 50 disease areas. He has published over 800 research articles and is ranked as being in the top 1% of the world’s most cited scientists by Thomson-Reuters. He held a prestigious European Research Council senior investigator award in epigenetics and is a NIHR Senior Investigator. His current work focuses on omics and the microbiome and directs the crowdfunded British Gut microbiome project. Together with an international team of leading scientists including researchers from King’s College London, Massachusetts General Hospital, Tufts University, Stanford University and nutritional science company ZOE he is conducting the largest scientific nutrition research project, showing that individual responses to the same foods are unique, even between identical twins. You can find more on https://joinzoe.com/ He is a prolific writer with several popular science books and a regular blog, focusing on genetics, epigenetics and most recently microbiome and diet (The Diet Myth). He is in demand as a public speaker and features regularly in the media.
LOS ANGELES — Modifying 12 risk factors over a lifetime could delay or prevent 40% of dementia cases, according to an updated report by the Lancet Commission on dementia prevention, intervention and care presented at the Alzheimer’s Association International Conference (AAIC 2020).
Twenty-eight world-leading dementia experts added three new risk factors in the new report — excessive alcohol intake and head injury in mid-life and air pollution in later life. These are in addition to nine factors previously identified by the commission in 2017: less education early in life; mid-life hearing loss, hypertension and obesity; and smoking, depression, social isolation, physical inactivity and diabetes later in life (65 and up).
Schneider and commission members recommend that policymakers and individuals adopt the following interventions:
Aim to maintain systolic blood pressure of 130 mm Hg or less from the age of 40.
Encourage use of hearing aids for hearing loss and reduce hearing loss by protecting ears from high noise levels.
Reduce exposure to air pollution and second-hand tobacco smoke.
Prevent head injury (particularly by targeting high-risk occupations).
Limit alcohol intake to no more than 21 units per week (one unit of alcohol equals 10 ml or 8 g pure alcohol).
Stop smoking and support others to stop smoking.
Provide all children with primary and secondary education.
Lead an active life into mid-life and possibly later life.
Reduce obesity and the linked condition of diabetes.
“The findings of this study are promising and reinforce what we’ve seen in other studies — fasting diets are a viable option for people who want to lose weight, especially for people who do not want to count calories or find other diets to be fatiguing,” Varady said.
…participants in both daily fasting groups reduced calorie intake by about 550 calories each day simply by adhering to the schedule and lost about 3% of their body weight. The researchers also found that insulin resistance and oxidative stress levels were reduced among participants in the study groups when compared with the control group.
Two daily fasting diets, also known as time-restricted feeding diets, are effective for weight loss, according to a new study published by researchers from the University of Illinois at Chicago.
The study reported results from a clinical trial that compared a 4-hour time-restricted feeding diet and a 6-hour time-restricted feeding diet to a control group.
“This is the first human clinical trial to compare the effects of two popular forms of time-restricted feeding on body weight and cardiometabolic risk factors,” said Krista Varady, professor of nutrition at the UIC College of Applied Health Sciences and corresponding author of the story.
“On a high-sugar diet, we find that the fruit flies’ dopaminergic neurons are less active, because the high sugar intake decreases the intensity of the sweetness signal that comes from the mouth,” Dus said. “Animals use this feedback from dopamine to make predictions about how rewarding or filling a food will be. In the high-sugar diet flies, this process is broken—they get less dopamine neuron activation and so end up eating more than they need, which over time makes them gain weight.”
It is well known that consuming food and drink high in sugar is not great for us, but scientists are continuing to unravel the intricacies of how the sweet stuff drives negative health outcomes. The latest finding comes from researchers at the University of Michigan, who through studies in fruit flies have found that excess amounts of sugar can shut down crucial neural circuits linked to regulating satiety, possibly leading to overeating in humans.
From The Lancet Diabetes & Endocrinology (June 2020):
Our findings show that the intensive lifestyle intervention led to significant weight loss at 12 months, and was associated with diabetes remission in over 60% of participants and normoglycaemia in over 30% of participants. The provision of this lifestyle intervention could allow a large proportion of young individuals with early diabetes to achieve improvements in key cardiometabolic outcomes, with potential long-term benefits for health and wellbeing.
Type 2 diabetes is affecting people at an increasingly younger age, particularly in the Middle East and in north Africa. We aimed to assess whether an intensive lifestyle intervention would lead to significant weight loss and improved glycaemia in young individuals with early diabetes.
Between July 16, 2017, and Sept 30, 2018, we enrolled and randomly assigned 158 participants (n=79 in each group) to the study. 147 participants (70 in the intervention group and 77 in the control group) were included in the final intention-to-treat analysis population. Between baseline and 12 months, the mean bodyweight of participants in the intervention group reduced by 11·98 kg (95% CI 9·72 to 14·23) compared with 3·98 kg (2·78 to 5·18) in the control group (adjusted mean difference −6·08 kg [95% CI −8·37 to −3·79], p<0·0001). In the intervention group, 21% of participants achieved more than 15% weight loss between baseline and 12 months compared with 1% of participants in the control group (p<0·0001). Diabetes remission occurred in 61% of participants in the intervention group compared with 12% of those in the control group (odds ratio [OR] 12·03 [95% CI 5·17 to 28·03], p<0·0001). 33% of participants in the intervention group had normoglycaemia compared with 4% of participants in the control group (OR 12·07 [3·43 to 42·45], p<0·0001).
…ultra-processed foods are generally the foods available to nurses working nightshifts, firefighters returning to their department after a call, police officers patrolling neighborhoods, or military soldiers during field-exercises. Thus, time-restricted eating removes the added stress of what to eat, and serves as a practical intervention conducive to the schedules of many people.
Time-restricted eating has been shown to lower circulating insulin, blood pressure, body fat and overall body weight, inflammation, and oxidative stress.
Time-restricted eating is a nutrition intervention which alternates between a period of fasting (12 – 16 hours) followed by a period of eating (8 – 12 hours). Unlike other diets, which focus on the caloric content of a meal or which foods you should eat, time-restricted eating focuses exclusively on when you eat by compressing and standardizing the feeding window each day. In turn, people following this type of eating pattern naturally enter a state of caloric deficit.
Obesity is at the root of silent epidemics such as type 2 diabetes and nonalcoholic fatty liver disease.
Laura Schmidt explores the causes and solutions, taking lessons from tobacco: reducing the availability of harmful substances reduces consumption, thereby reducing harms to health. She talks about the UCSF Healthy Beverage Initiative and the effects it has had on employee health.
Compared with usual diet, moderate certainty evidence supports modest weight loss and substantial reductions in systolic and diastolic blood pressure for low carbohydrate (eg, Atkins, Zone), low fat (eg, Ornish), and moderate macronutrient (eg, DASH, Mediterranean) diets at six but not 12 months. 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 (fig 6) without concern about the magnitude of benefits.
The worldwide prevalence of obesity nearly tripled between 1975 and 2018.1 In response, authorities have made dietary recommendations for weight management and cardiovascular risk reduction.23 Diet programmes—some focusing on carbohydrate reduction and others on fat reduction—have been promoted widely by the media and have generated intense debates about their relative merit. Millions of people are trying to lose weight by changing their diet. Thus establishing the effect of dietary macronutrient patterns (carbohydrate reduction v fat reduction v moderate macronutrients) and popular named dietary programmes is important.
Biological and physiological mechanisms have been proposed to explain why some dietary macronutrient patterns and popular dietary programmes should be better than others. A previous network meta-analysis, however, suggested that differences in weight loss between dietary patterns and individual popular named dietary programmes are small and unlikely to be important.4 No systematic review and network meta-analysis has examined the comparative effectiveness of popular dietary programmes for reducing risk factors for cardiovascular disease, an area of continuing controversy.