What was going on when I was born?

THE more scientists study the problem of overweight and the difficulty of shedding extra pounds, the more it seems that brain and body chemistry control the outcome. Stores of fat in the body increase when food intake is persistently greater than the body's energy use, but controls over this are complex. They involve a constellation of hormonal and nervous system factors, orchestrated ultimately by the hypothalamus, a deep-seated portion of the brain that is involved with emotion as well as basic physiological controls. By studying such controls and the ways in which they can go awry, scientists look toward a future that might provide new approaches to mastering obesity. The attention of many scientists today is focused on the biochemical controls over the fat cells and related aspects of fat storage.

In the wilderness of the Empty Quarter, amid red sand dunes that rise hundreds of feet and where the mercury can soar above 140 degrees, the working day never ends for Don Harday and Roy Korbut, both Canadian nationals. On an around-theclock basis, they drill for oil, certain that it lies miles below these sandy wastes but unsure exactly where. Drilling for oil here is difficult business, and so, too, is getting drillers to come to Saudi Arabia, according to the Arabian American Oil Company, which produces nearly all the crude oil in this country of eight million people. Because of the problems in finding workers Aramco has embarked on a new recruiting drive in the United States and Europe and is stepping up its program to recruit and train Saudi nationals.

The house that Darryl F. Zanuck built contains far more riches than meet the casual eye. The rabid interest among a band of corporate suitors of the 20th Century-Fox Film Corporation stretches beyond a simple desire to be part of the glitter and glamour of making movies. Tucked within the framework of the big film company is a bevy of lucrative assets, including some of the choicest real estate in the world, most of which is carried on the Fox books at well below what the assets might fetch in today's marketplace. It comes as little surprise, then, that Marvin Davis, a Denver oil millionaire, has offered close to $700 million to buy Fox. ''If you took all the assets of this company and sold them off piecemeal,'' says Anthony Hoffman, a securities analyst at A.G. Becker, ''you'd probably get a good deal more money than Mr. Davis is preparing to pay.''

Faced with increasing competition from cheaper sources of credit, most of the nation's large banks yesterday reduced their prime lending rates by half a percentage point, to 19 percent, and several dropped to the 18 1/2 percent level. Bankers cautioned that yesterday's decline in this key rate did not necessarily indicate that lending rates would drop further. They said they remained wary about the immediate economic outlook, and they also expressed concern about President Reagan's economic program. ''We have a nagging fear that the recent leveling off of the money supply will turn around again because the economy has been behaving so much more strongly than we had expected,'' said Frederick W. Deming, senior vice president of the Chemical Bank.

Despite unhappiness about proposed cuts in Federal funds for Medicaid, the Governors of 48 states met today with President Reagan to assure him that they generally supported his efforts to ''restore balance to the Federal system,'' as Gov. George Busbee of Georgia put it. Mr. Busbee, chairman of the National Governors Association, said the Governors were as determined as the President to see that the role of the states was enhanced and the Federal Government's influence reduced. Difference of Opinion But he said they had told Mr. Reagan that they took a view different from his on how to carry out those goals, believing that while the states should be responsible for law enforcement or education, the Federal Government should pay the costs of such transfer payment programs as welfare and Medicaid, the Federal-state program that pays health-care costs for the poor. Mr. Busbee said it was clear that Mr. Reagan did not now believe in a strong Federal role in Medicaid or welfare. ''But,'' he said, ''they're listening and we're making our points.'''

An infection of the heart, presumably from a virus, caused the death earlier this month of one young boy who attended the Chestnut Hill School in Dix Hills, L.I., and is suspected to be the cause of the death of another, according to Dr. Minoru Araki, deputy chief medical examiner of Nassau County. No virus has yet been detected in either case, and Dr. Araki, who is a pathologist, said yesterday that the chances of identifying a specific virus ''are very slim at best.'' Even so, Dr. Araki said he did not believe there was a threat to public health. Such cases often occur in a community on a sporadic basis, he said.

Directors of GK Technologies called a special board meeting last night to consider a friendly takeover bid from the Penn Central Corporation involving an estimated $715 million or more in cash, well-placed Wall Street sources disclosed. Penn Central's offer - considerably sweetened from two prior bids - was reported to involve roughly $50 a share for GK's 12.2 million shares of common stock plus some $60 a share for its 1.75 million shares of preferred stock. There was no indication, however, how GK's board of directors would vote on the proposal; earlier in the day, in a move that suggested agreement was very close, GK said it had asked the New York Stock Exchange to halt trading in its stock ''pending an announcement with regard to its discussions with the Penn Central Corporation.''

ASOMETIMES angry tug-of-war is underway among medical researchers, medical reporters and the editors of some medical journals. Depending on who is talking, the prize is more accurate public information about medical advances, professional recognition and possibly commercial gain for the researchers, or simply first crack at the best stories. The fight, heated by misunderstandings on all sides, raises several issues: when and how medical information is or ought to be disseminated; whether those decisions are best left to the experts or to workaday journalists, and; how much the public has a ''right'' to know about scientific research. The controversy has been provoked by Dr. Arnold S. Relman, editor of one of the country's most eminent scholarly medical publications, The New England Journal of Medicine, published in Boston by the Massachusetts Medical Society. Dr. Relman contends that much of what now passes for medical news in the lay press is the unverified and often overly optimistic hypotheses of researchers. The public would get more reliable information, he says, if reporters for the lay and medical press would wait until research has been verified through a process of peer review and published in scientific journals, such as his own. Doctors, he says, would not have to contend with patients who might have read about some new ''cure'' that the lay press reports but which the journals find does not stand up to professional scrutiny or hasn't yet been published in the journals.

The Supreme Court agreed today to decide whether private investors are entitled to sue commodity brokers and exchanges for damages that result from market manipulation or fraud. The Justices accepted an appeal by the New York Mercantile Exchange and two commodity brokers from a ruling by a Federal appeals court that the Commodity Exchange Act allows private damage suits as well as enforcement action by the Commodity Futures Trading Commission. Under that ruling, the exchange and the brokers must stand trial in a $1.3 million damage suit growing out of a major default five years ago in the market for Maine potato futures. The sellers of almost 1,000 futures contracts failed to deliver 50 million pounds of potatoes, the largest default in the history of commodity futures trading in the United States.

''Since the change of leadership in the White House, candidly bellicose calls and statements have resounded from Washington, especially designed, as it were, to poison the atmosphere of relations between our two countries.

DESPITE the national obsession with diets and dieting, 80 million Americans are overweight and, a recent national survey showed, the average person today is fatter than ever before. So are the coffers of a largely unregulated $10-billion industry that purports to assist people in shedding unwanted pounds via drugs, devices, salons, special foods and a never-ending stream of best-selling diet schemes. While the desperate resort to such extremes as prolonged fasts, stapling the stomach, jaw wiring and intestinal bypass surgery, the majority of weight-conscious Americans hop from one fad diet to another searching vainly for a shortcut to slimness, and sometimes jeopardizing their health in the process. Yet, experts report, 80 to 90 percent of dieters soon regain lost pounds and often then some, only to try still another diet in what the nutritionist Dr. Jean Mayer has dubbed ''the rhythm method of girth control.'' ''If there was an effective diet,'' said Dr. George A. Bray of the University of California at Los Angeles, ''there would be no need for the continuous introduction of new diets: the 'Grapefruit Diet,' the 'Drinking Man's Diet,' the 'Air Force Diet,' the 'Mayo Diet,' the 'Quick Weight Loss Diet' and so on. It seems obvious from the number of diets that have been made available and are continuing to appear, none of them provides the answer to obesity.''

After more than two hours of sometimes emotional debate, the Republican-led State Senate voted today to give welfare recipients a 15 percent increase in the basic grant that they receive each month. The vote was 34 to 24. Broad support from Democrats was supplemented by Republican moderates and anti-abortion conservatives who heeded Senator John J. Marchi's call to ''recognize the plight not of the greedy, but of the needy.'' The bill would increase the basic public assistance grant for a family of four to $296 a month. The current basic grant of $258 was fixed in 1974, to reflect the 1972 cost of living, and has not been increased since then. Under the Senate plan, whose chief sponsor was the majority leader, Warren M. Anderson, Republican of Binghamton, the state would pay the entire cost of the increase.