here are 2 recent AHA guidelines, obesity and lifestyle. less controversial than the other ones….
1. obesity (see link: http://circ.ahajournals.org/content/early/2013/11/11/01.cir.0000437739.71477.ee.citation )
recommendations:
in terms of assessing obesity, calculate BMI at least annually, using the current cutpoints of overweight as 25-30 and obesity greater than 30, noting that overweight identifies people at elevated risk of cardiovascular disease and obesity identifies those at elevated risk of mortality from all-causes. These are grade B recommendations. Another grade B recommendation was to measure waist circumference at annual visits, supported by expert opinion. studies have found that waist circumference more accurately reflects visceral fat than BMI does, and visceral fat correlates with insulin resistance, lipid markers (LDL, HDL), inflammatory markers (crp and other cytokines), thrombotic markers, as well as with adverse clinical events. in fact the defn of metabolic syndrome (which is assoc with all-cause and CAD mortality even in those without diabetes) in the US includes 3 of: central obesity (men waist circumference >40 inches, women >35), fasting triglycerides>150, HDL<40 men or <50 women, BP>130/85, or fasting glucose >110. The International DM Federation in 2005 defined it as increased waist circumference (a necessary item) plus any 2 of the above (though they use fasting glucose cutpoint of 100). they note that metabolic syndrome is defined differently in different ethnic groups: eg European ancestry men 94 cm (37 inches), women 80 (33.5 in); S Asian and Chinese men 90 (35.5 in) and women 80 (31.5 in); Japanese men 85 cm (33.5 in) and women 90 (35.5 in). not enough data for other ethnicities. overall (though absolutely not always) those with BMI >30 do have visceral obesity as well, so may not need waist circumference measured (though a quick glance is likely to reveal if the fat distribution is central/waist vs peripheral/hips and buttocks).
sustained weight loss of 3-5% is associated with clinically meaningful reductions in triglycerides, blood sugar, A1c, and the risk of developing diabetes. (so, it is important for patients to be aware that even small amounts of weight loss are physiologically beneficial)
prescribe diet with restricted calories, especially one with a 500-750 kcal per day energy deficit. they are not specific in choice of diet, just one that restricts either high carbohydrate foods, low fiber foods, or high-fat. (from my review, there are reasonable data that low glycemic index diet unrestricted in kcal intake by itself lowers calorie intake, roughly equivalent to a 500 kcal restricted low-fat diet).
best to have an overall comprehensive lifestyle program, encourage patients to adhere to a low calorie diet and increased physical activity through the use of behavioral strategies. This also includes people who have already lost significant amounts of weight, as a means to maintain the weight loss. They also suggest the use of face-to-face or telephone delivered weight loss maintenance programs as well as the potential benefit of electronically delivered programs
consider bariatric surgery in patients with a BMI greater than 40 or greater than 35 with obesity-related comorbidities
for these panel participants, both co-chairs and half of the committee members had significant drug company support.
2. lifestyle ( see link: http://circ.ahajournals.org/content/early/2013/11/11/01.cir.0000437740.48606.d1.citation). General recommendations:
–For adults who would benefit from LDL lowering: Consume a diet high in vegetables, fruits, and whole grains; low-fat dairy products, poultry, fish, legumes, nontropical vegetable oils and nuts; and limit sweets, sugar-sweetened beverages, and red meats. Overall, only 5-6% of calories should be from saturated fats. Reduce trans-fats.
–for adults who would benefit from blood pressure lowering: Consume a diet similar to above; limit sodium intake, consuming no more than 2.4 g per day, though they do note that lowering sodium to 1 to 1.5 g per day will lead to greater reduction of blood pressure.
–for both blood pressure and LDL reduction, exercise with moderate to vigorous intensity physical activity, 3-4 sessions per week, lasting 40 min. per session.
Although they note that there are different definitions of a Mediterranean diet, the common features include: high fresh fruit intake; root and green vegetables; whole grains (cereals, breads, rice, or pasta); fatty fish rich in omega-3 fatty acids; minimizing red meats and emphasizing lean meats; lower fat dairy products; olive and canola oils; walnuts, almonds or hazelnuts.
DASH diet also has many variations. In general similar to the Mediterranean diet in content, with variations to decrease the glycemic load of the diet, for example replacing 10% of calories from carbohydrates with either protein or unsaturated fats. They do not feel there is evidence to determine whether low glycemic diet affects lipids or blood pressure in adults without diabetes. (The data are pretty clear to me that low glycemic index diet pretty consistently improves total cholesterol-to-HDL ratio in diabetics, see for example Jenkins et al JAMA 2008;300:2742). One concern that I have with the DASH diet is that the emphasis on polyunsaturated fats in the earlier versions tends to depress HDL, the later iterations focus on monounsaturated fats which tend to raise the HDL. again, as in the lipid guidelines sent out previously, these guidelines do not incorporate HDL, though ironically it is a major determinant in their risk calculator, as in the Framingham study one.) for hypertension, combo of DASH and low salt is additively beneficial.
in terms of sodium and potassium, they note that reducing sodium lowers blood pressure, with a decrease from 3.3 g a day to 2.4 g per day lowering the blood pressure by 2/1 mmHg, lowering sodium to 1.5 g a day lowers the blood pressure by 7/3 mmHg. They also comment that decreasing to 1.15 g a day reduces the blood pressure by 3-4/1-2 mmHg. their review suggests that lowering his sodium intake by 1 g per day reduces cardiovascular disease events by 30%. They do not feel that there are sufficient intervention trials with potassium to suggest changing dietary potassium, though they do note there are strong observational studies finding a benefit to high potassium diets. Of note I sent out the Institute of the Medicine report in May suggesting that lowering dietary sodium below 2.3 g a day might be harmful, will repost that on blog.
they support exercise to lower her LDL, non-HDL, and both systolic and diastolic blood pressure. see recommendation above.
they note as areas needing further research: Interaction between dietary change and statins, relative effects of naturally occurring fiber and supplemental fiber on lipids and other cardiovascular risk factors, effects of minerals other than sodium on blood pressure, clinical effects of raising HDL through diet, specific patterns of exercise that affect lipids maximally, why the studies on exercise and HDL produce inconsistent findings, and more data on the synergy of physical activity with diet and or lipid lowering medications.
it is interesting in comparing this guideline with all the others (eg the one on lipids), essentially none of the board members in this lifestyle guideline have any conflict of interest.
geoff